GOLDEN VIEW DRIVE RABBIT CREEK ROAD TO ROMANIA DRIVE GOLDEN VIEW DRIVE INTERSECTION & SAFETY UPGRADES Design Study Report PRE-FINAL May 2013 MOA Project No. 10-026 Prepared for: Municipality of Anchorage, Public Works Department, Project Management & Engineering Division, 4700 Elmore Road, Anchorage, Alaska 99507 Prepared by: CRW Engineering Group, LLC 3940 Arctic Blvd. Suite 300 Anchorage, Alaska 99503 www.crweng.com
Executive Summary Introduction The Municipality of Anchorage Project Management and Engineering (MOA PM&E) has contracted with CRW Engineering Group, LLC to provide professional services to evaluate alternatives to upgrade Golden View Drive from Rabbit Creek Road to Romania Drive to current Municipal collector road standards. This project is the number one priority for the Rabbit Creek Community Council and a high priority for the South Goldenview Area Rural Road Service Area, the Anchorage School District, the Traffic Engineering Division, and the surrounding neighborhoods. Currently, the project has been funded with a $3 million State grant for design and pre-construction tasks. Additional bond funding and State grants will be necessary for ROW acquisition and construction. Based on public and agency stakeholder input during the Concept Report Phase, the primary goals of this project are as follows, in no particular order of importance: Improve the roadway to meet current MOA standards. Improve area drainage while maintaining creeks and flows to wetlands. Improve pedestrian and bicycle safety. Improve Golden View Drive/Bluebell Drive intersection. Evaluate solutions to address traffic congestion during peak hours on Golden View Drive resulting from Goldenview Middle School traffic. Address speeding on Golden View Drive. The Design Study Report evaluates existing and future conditions and a range of conceptual design alternatives. Recommended Improvements The recommended typical cross section consists of two 11-foot lanes with 3.5-foot shoulders and barrier curb and gutter. A single pedestrian facility is recommended: an 8-foot wide paved pathway located on the west side, separated from the back of curb where feasible. A drainage swale would be located on the east side. Executive Summary (May 2013) - 1 -
Golden View Drive Typical Section Other recommended improvements include: Posted Speed Limit: Based on recommendations from the Traffic Division and approved by the Planning and Zoning Commission, the posted speed limit is to be increased from 35 MPH to 40 MPH. Landscaping: Proposed landscaping will be in character with the adjacent residential properties which is native in aesthetics. The focus will be on preserving existing vegetation to the greatest extent practical, supplementing the landscaping with new plantings when appropriate. Retaining Walls: Retaining walls are recommended, as appropriate, to minimize impacts to adjacent utilities, properties, or the environment. Lighting: A continuous roadway LED lighting system, current with MOA standards, is proposed. Storm Drain: The proposed drainage system is made up of five separate systems, each with their own outfall. Site topography and existing stream and drainages necessitate using separate systems. A large diameter storm drain main will extend along a majority of the project length, serving as both a roadway runoff collection system, and high runoff bypass system. Existing stream and drainage crossing structures will be replaced and upgraded as required by modifications to the roadway cross section. Following is a summary of conceptual estimated costs for the proposed improvements for Golden View Drive Upgrades. Executive Summary (May 2013) - 2 -
Schedule Total Roadway & Sidewalk Improvements 1 $9,114,000 Storm Drainage Improvements $4,877,000 Illumination and Electrical Improvements $1,432,000 Landscaping $480,000 Subtotal Construction = $15,903,000 Contingency (20%) $3,181,000 Total Construction = $19,084,000 Utility Relocation $2,582,000 ROW Acquisition $100,000 Total = $21,766,000 Notes: 1. Estimated costs do not include improvements to Bluebell Drive. 2. Estimated construction and ROW acquisition costs do not include Rabbit Creek Road / Golden View Drive Intersection as this work will be dependent on the outcome of a future study being done by ADOT. Executive Summary (May 2013) - 3 -
Table of Contents I. Introduction... 1 A. Concept Report Summary/Project Goals... 1 II. Existing Conditions... 5 A. Area Context... 5 B. Facility Description... 5 C. Land Use and Ownership... 9 D. Geotechnical Summary... 9 E. Environmental... 11 F. Drainage... 13 G. Vegetation/Landscaping... 17 H. Utilities... 18 1. Water... 18 2. Sewer... 19 3. Natural Gas... 20 4. Electric... 21 5. Telephone... 22 6. Cable Television... 22 III. Traffic and Safety Analysis...24 A. Existing Traffic Volume & Speed Data... 24 B. Traffic Projections... 27 C. Traffic Characteristics... 30 D. Crash Data... 31 E. Operational Analysis... 32 1. Segment Analysis Golden View Drive... 32 2. Intersection Analysis... 33 F. Side Street Intersections/Access Control... 34 IV. Stakeholder/Public Involvement...34 V. Design Criteria...36 A. Design Standards... 36 1. Municipality of Anchorage... 37 2. State of Alaska... 37 3. Federal... 37 B. Design and Posted Speed... 38 School Speed Zone:... 39 C. Accessibility Guidelines... 39 D. Typical Section... 39 E. Clear Zone... 40 F. Lighting... 40 G. Landscaping... 41 H. Design Criteria Summary... 43 VI. Design Alternatives...44 A. Design Challenges... 44 B. Golden View Drive Alignment and Profile... 45 1. Golden View Drive Profile... 45 May 2013 i
2. Golden View Drive Profile at Bluebell Drive:... 47 C. Local Side Street Alignments and Profiles... 54 1. Golden View Drive, south of Romania Drive... 54 2. Bluebell Drive... 58 3. Ransom Ridge Road... 58 4. Horizontal Curves... 59 D. Roadway Cross Section... 60 E. Pedestrian Facilities... 62 1. Alternative 1: Pathway west side only... 62 2. Alternative 2: Pathway on west side, sidewalk on east side... 63 3. Alternative 3: Pathway west side, sidewalk on east side partial length... 63 4. Alternative 4: Pathway west side, sidewalk on east side partial length... 63 5. Alternative 5: Pathway east side only... 63 F. Side Street Intersections/Access Control... 65 G. Rabbit Creek Road/Golden View Drive Intersection... 65 H. Structural Section... 66 I. Retaining Walls... 67 1. Retaining Wall Types... 67 2. Considerations... 68 3. Estimated Project Cost... 72 J. Traffic Calming... 73 K. Lighting... 74 L. Landscaping... 76 M. Trails... 77 N. Cluster Mailboxes... 78 O. Parking... 78 VII. Drainage Analysis...79 A. Existing Planning Documents... 79 B. Storm Water Model... 79 C. Proposed Drainage System... 81 VIII. Right-of-Way Impacts...84 A. Overview... 84 B. Right-of-Way Easements/Permits... 85 IX. Design Recommendations...86 A. Roadway... 86 B. Structural Section... 86 C. Retaining Walls... 86 D. Drainage... 87 E. Traffic Calming... 87 F. Lighting... 87 G. Landscaping... 87 H. Design Cost Estimate... 88 May 2013 ii
List of Figures Figure 1 Location Map... 3 Figure 2 Project Vicinity Map... 4 Figure 3 Area Zoning, Roadway Classifications, and Bus Stops... 8 Figure 4 Wetlands Map...12 Figure 5 Existing Drainage Map...16 Figure 6 AWWU and HDP water and sewer service area boundary...20 Figure 7 Existing Peak Hour Turning Movement Counts...25 Figure 8 Projected AADT (design year 2033)...28 Figure 9 Projected Peak Hour Turning Movement Counts...29 Figure 10 Roadway profile split at Bluebell Drive...52 Figure 11 Proposed Grades along Golden View thru intersection with Romania...55 Figure 12 Sweep from Golden View Drive to Romania Drive...57 Figure 13 Proposed Typical Cross Section...61 May 2013 iii
List of Tables Table 1 Existing AADT Traffic Data...24 Table 2 Speed Study Results...26 Table 3 1999-2008 Crash Summary for Intersections on Golden View Drive...31 Table 4 Golden View at E. 156th & Prominence Pointe Operational Analysis...33 Table 5 Design Criteria Summary...43 Table 6 Summary of Retaining Walls (preferred alternative)...73 Table 7 Summary of storm water runoff...80 Table 8 Estimated Right-of-Way Easements/Permits...85 Table 9 Summary of Estimated Construction Costs...88 Appendices Appendix A: Appendix B: Appendix C: Appendix D: Appendix E: Appendix F: Appendix G: Appendix H: Appendix I: Appendix J: Appendix K: Concept Report Roadway Plan and Profile Sheets Existing Utilities Traffic Analysis Report and Data Geotechnical Analysis Drainage Analysis Rabbit Creek Road/Golden View Drive Intersection Alternative Report Bluebell Drive Design Study Memorandum Right-of-Way Analysis Cost Estimates Agency Review Comment Summary May 2013 iv
Abbreviations AADT AASHTO AASHTOGB ACS ADA ADEC ADF&G ADNR ADT ADOT&PF/DOT AFD AMATS AMC ASD ATP AWWU BOC CEA cfs CMP DCM DHV DIP DSR EB EOP GCI EPA ESCP HDPE IESNA ITE LOS MOA MPH MUTCD NB OS&HP PCM PCMP PM&E PUE ROW SB sf SWMM SWPPP TCP UDC USACE vpd WB WSM Annual Average Daily Traffic volume (vehicles per day) American Association of State Highway Transportation Officials AASHTO Policy on Geometric Design of Highways and Streets Alaska Communication Systems Americans with Disability Act Alaska Department of Environmental Conservation Alaska Department of Fish and Game Alaska Department of Natural Resources Average Daily Traffic volume (vehicles per day) Alaska Department of Transportation and Public Facilities Anchorage Fire Department Anchorage Metropolitan Area Transportation Solutions Anchorage Municipal Code Anchorage School District Areawide Trails Plan Anchorage Water and Wastewater Utility Back of curb Chugach Electric Association Cubic foot per second Corrugated Metal Pipe Municipality of Anchorage Design Criteria Manual Design Hour Volume Ductile Iron Pipe Design Study Report Eastbound End of Project General Communications, Inc. Environmental Protection Agency Erosion and Sediment Control Plan High density polyethylene pipe Illumination Engineering Society of North America Institute of Traffic Engineers Level of Service Municipality of Anchorage Miles per hour Manual of Uniform Traffic Control Devices Northbound Official Streets and Highways Plan ADOT&PF Pre-Construction Manual Pre-coated Corrugated Metal Pipe Project Management and Engineering Public Use Easement Right-of-way Southbound Square feet Storm Water Management Model Storm Water Pollution Prevention Plan Temporary Construction Permit Urban Design Commission US Army Corps of Engineers Vehicles per day Westbound Watershed Management May 2013 v
I. Introduction The Municipality of Anchorage Project Management and Engineering (MOA PM&E) has contracted with CRW Engineering Group, LLC to provide professional services to evaluate alternatives to upgrade Golden View Drive from Rabbit Creek Road to Romania Drive to current Municipal collector road standards. See FIGURES 1 AND 2 for Location and Project Vicinity maps. The scope of work includes a determination of appropriate design criteria to be used for the proposed improvements. This project is the number one priority for the Rabbit Creek Community Council and a high priority for the South Goldenview Area Rural Road Service Area (RRSA), the Anchorage School District, the Traffic Engineering Division, and the surrounding neighborhoods. Currently, the project has been funded with a $3 million State grant for design and pre-construction tasks. Additional bond funding and State grants will be necessary for rightof-way (ROW) acquisition and construction. A. Concept Report Summary/Project Goals Using the MOA Context Sensitive Solutions (CSS) Policy as a guideline, the Golden View Drive Intersection and Safety Upgrades Concept Report was prepared. The goal of the CSS process is to collaborate with stakeholders to improve the safety and mobility of the corridor, balance diverse interests, and to find areas of compromise that address budget and environmental concerns. The CSS policy provides guidelines to involve project stakeholders in defining the problems to be solved and a conceptual range of potential solutions to address the problems. The full Concept Report and range of stakeholder activities can be found in APPENDIX A. The CSS process will continue throughout the design phase of the project with additional opportunities for stakeholders to obtain information and provide feedback through the web page, e-newsletter updates, open houses, community council presentations, and direct feedback through phone calls and e-mail. May 2013 1
Based on public and agency stakeholder input during the Concept Report Phase, the primary goals of this project are as follows, in no particular order of importance: Improve the roadway to meet current MOA standards. Improve area drainage while maintaining creeks and flows to wetlands. Improve pedestrian and bicycle safety. Improve Golden View Drive/Bluebell Drive intersection. Evaluate solutions to address traffic congestion during peak hours on Golden View Drive resulting from Goldenview Middle School traffic. Address speeding on Golden View Drive. The community also placed a high importance on improving the Rabbit Creek Road/Golden View Drive intersection. The Rabbit Creek Road/Golden View Drive Intersection Alternative Report was prepared as part of the initial Design Study Phase; however, further work on the intersection is pending a study by the Alaska Department of Transportation (ADOT) of all of the hillside intersections. To achieve the above goals, the Design Study Report (DSR) evaluates the need for the improvements to the roadway and pedestrian facilities, surface and subsurface drainage, pedestrian and vehicular connectivity, landscaping, signalization, and lighting. The No Build alternative is not considered in this report as it is not supported by project stakeholders and does not address the problems that need to be resolved. May 2013 2
ELMORE GOLDEN VIEW DRIVE MOA Project #10-026 PROJECT LOCATION Knik Arm ³ Anchorage, AK Turnagain Arm RABBIT CREEK ROAD M O U N TAIN AIR OLD SEWARD SEWARD HWY Figure 1 - Project Location Map Pre Final Design Study Report May 2013 3
II. Existing Conditions A. Area Context Land uses are a mix of large lots with lower density residential served by private wells and septic, and newer subdivisions served by water and sewer that are more dense (Prominence Pointe and Golden View Park). There are also significant tracts of undeveloped, residentially-zoned land near the south end of Golden View Drive and at the southeast corner of Golden View Drive and Rabbit Creek Road. Moen Park, a 10-acre neighborhood park near the south end of the corridor, has play equipment for toddlers and a small parking lot. Golden View Middle School is located at the northern end of the corridor. Students attending Goldenview Middle School, Bear Valley Elementary School and South Anchorage High School are all bussed from stops along Golden View Drive. Golden View Drive is also the only winter access to Paradise Valley, a neighborhood at the south end. Area zoning is a mix of newer subdivision and lower density, larger lots. Little Survival Creek and Little Rabbit Creek along with associated wetlands, tributaries, and multiple drainage channels meander throughout the project area. Topography is generally steep providing views towards the Anchorage Bowl and Cook Inlet. Vegetation along the corridor is typically a mix of birch, spruce and alder and often provides a buffer between homes and the roadway. Moose and bear frequent the area. B. Facility Description Golden View Drive is a collector roadway on the Anchorage hillside that serves several adjacent residential neighborhoods and Goldenview Middle School. Golden View Drive was annexed into the Anchorage Roads and Drainage Service Area (ARDSA) in 2008; however, May 2013 5
the adjacent parcels and the roads to the west and east are still in the South Goldenview Area RRSA. The existing roadway has two 11-foot wide, strip-paved lanes with a 2-foot wide gravel shoulder on the east side. On the west side, there is: A 100-foot long separated asphalt pathway that extends south from Rabbit Creek Road along the west side of Golden View Drive (see photo, right); A 6-foot wide paved, designated bicycle lane from Rabbit Creek Road to Bridgeview Drive; And south of Bridgeview Drive, there is an 8-foot wide gravel shoulder. Separated pathway at Rabbit Creek Road/ Golden View Drive intersection There are no other pedestrian/non-motorized facilities along Golden View Drive. ASD has designated Golden View Drive as a hazardous walking route due to the lack of pedestrian/bicycle facilities. As a result, all students attending Goldenview Middle School are bussed. There is a northbound right turn lane at the Rabbit Creek Road intersection and the posted speed along the corridor is 35 MPH. The public ROW varies between approximately 60 to 80 feet for the majority of the project corridor; however, the ROW width is 100 feet north of the Rabbit Creek culvert and also just north and south of Bluebell Drive. May 2013 6
Rabbit Creek Road is a state-owned minor arterial west (downhill) of Golden View Drive and a collector to the east (uphill). It has two 12-foot travel lanes with 6-foot shoulders. There are channelized eastbound left and right turn lanes onto Golden View Drive. There is also a channelized westbound left turn onto Golden View Drive. The posted speed limit is 45 MPH. There are no pedestrian or non-motorized facilities along Rabbit Creek Road near the project corridor. People Mover Transit does not currently serve Golden View Drive. The nearest bus stop is Route 60 along the Old Seward Highway and Huffman Road. Rabbit Creek Road at Golden View Drive, looking west Anchorage School District has bus stops for Bear Valley Elementary School (Route #13), Golden View Middle School (Route #27), and South Anchorage High School (Route #14) to serve students living on Golden View Drive and adjacent neighborhoods. The busses stop at E. 172 nd Avenue, Ransom Ridge Road, Prominence Pointe Drive, E. 164 th Avenue, E. 162 nd Avenue, and E. 156 th Avenue. Busses use the mailbox pullout south of Bluebell Drive to turn-around. Parents frequently park along Golden View Drive to wait for their children to be picked up or dropped off from the busses. May 2013 7
Bettijean Luna Elizabeth Ashland Feodosia Betty Saint John's Saint James Wind Song Wills Buffalo Pollock Evergreen Ridge Golden View Golden View Drive Mesa MOA Project #10-026 w Jensen R-7 Longbow Stanwood Hillandale Noble Point R-3 SL R-6 Cape Seville Seville Manytell Neighborhood Collector (Class IC) Minor Arterial (Class II) Collector (Class I) PLI Ricky Bridgeview E. 156th cp Azalea Rabbit Creek Road R-9 Robin Hood E. 160th Blair View R-7 Andover Far View Cloudcroft Collector (Class I) R-6 SL R-10 SL Sandpiper Snow Flake R-9 Neighborhood Collector (Class IB) ³ Essex Park R-6 R-7 Aries Woodridge Virgo Belarde PLI Davis E. 164th Stone Ridge E. 172nd Marijane Ransom Ridge cp cp cp Woods Pointe E. 162nd cp cp R-7 Prominence Pointe Bluebell Briarcliff Ridge R-7 SL Briarcliff Pointe R-6 Shangri-La R-7 SL Cobblestone Hill Lost Horizon R-10 SL LEGEND Project Area ASD School Bus Stop Parks PLI = Public Lands & Institutes cp R-3 SL Kallander PLI R-9 PLI SL = Public Lands, Special Limitations R-3 SL = Multi Family Residential, Special Limitations R-6 = Suburban Residential R-6 SL = Suburban, Special Limitations R-7 = Intermediate Rural Residential R-7 SL = Intermediate Rural, Special Limitations R-9 = Rural Residential R-10 SL = Residential Alpine, Special Limitations Local Road Collector Road Minor Arterial PLI-p Austria Romania Spain Norway Rosemont R-3 SL R3-SL R-6 PLI Figure 3 - Area Zoning, Roadway Classifications, & Bus Stops Switzerland R-6 Steamboat Mountainside Village R-10 SL Pre Final Design Study Report May 2013 8
C. Land Use and Ownership Land uses within the corridor are predominately residential with the exception of Goldenview Middle School and Moen Park. A substantial amount of residentially-zoned land is undeveloped. Zoning is predominately R-6 (Suburban Residential large lot), R-7 (Intermediate Rural), R- 9 (Rural Residential), and R-3SL (Multiple Family Residential with special limitations on development). The school and park are zoned PLI (Public Lands and Institutions). Zoning is shown in FIGURE 3. The capacity for growth includes a combination of infill of small lots scattered along the corridor and the development of large tracts of land. There is a reserved elementary school site located just west of the middle school. Some other potential projects include platted and recorded development for Prominence Pointe Phase 1 expansion (142 lots) and Shangri-La (22 lots). Other significant areas of planned development include Forest Heights/ Legacy Point and Views of Prominence which will both have denser residential Aerial view of Golden View area (looking west) development. D. Geotechnical Summary Subsurface conditions are general composed of the structural road section overlying sand and gravel with varying amounts of silt. Soils generally consist of the following (also see APPENDIX E): Station 508+00 to 520+00: low to high frost susceptible (F1/F2 to F3) poorly graded sands and gravels and silty sand with gravel. There are also areas of shallow weathered rock, between 2.5 feet below ground surface (bgs) to 12 feet bgs. Cobbles were encountered in all four borings in the existing roadway structural section. Groundwater was observed in two borings at 6.8 feet and 13 feet bgs. May 2013 9
Station 520+00 to 537+00: low to moderate frost susceptible (F1 to F2) poorly graded sands and gravels, silty sand with gravel, and areas of high frost susceptible soils (F2/F3). Cobbles were encountered in four of the five borings in the existing roadway structural section. Groundwater was encountered in three of the borings at 4 feet, 11 feet, and 16 feet bgs. Station 537+00 to 585+00: non-frost to high frost susceptible (NFS to F3) poorly graded sands and gravels, silty gravel with sands, and silty sand with gravel. Peat was encounter in two borings at 16 feet bgs and 2.5 feet bgs. Cobbles were encountered in the majority of the borings in the existing roadway structural section. Groundwater was observed in ten of the borings at between 7 and 14.5 feet bgs. Station 585+00 to 601+00: low to high frost susceptible (F1 to F2/F3) poorly graded sands and gravels, silty gravel with sand, and silty sand with gravel. Cobbles were encountered in seven of the eight all of the boreholes. Groundwater was observed in four of the eight of the boreholes, at depths of between 6.3 feet and 15 feet bgs. Piezometers were installed in selected boreholes and follow up groundwater measurements taken between August and October 2011 indicated that the groundwater rose considerably in all but one of the 33 borings. Little Rabbit Creek May 2013 10
E. Environmental Based on a review of the Anchorage Wetlands Management Plan and the MOA Wetlands Atlas, 2008 Edition, there are numerous mapped wetland and streams within the project corridor (FIGURE 4). Little Survival Creek and Little Rabbit Creek along with associated wetlands, tributaries, and multiple drainage channels meander throughout the project area. Both Little Rabbit Creek and Little Survival Creek are listed as Impaired Water Bodies by the ADEC for fecal coliform bacteria resulting from urban runoff. As such, these creeks require measures to maintain and restore the creek s water functions. The project team held a meeting with the U.S. Army Corps of Engineers (USACE) on December 6, 2011 to introduce the project and discuss options to avoid, minimize, and mitigation potential impacts to jurisdictional waters of the U.S. Based on initial information and observations, it should be anticipated that the majority of the drainage channels will be jurisdictional waters and the USACE will be concerned about maintaining flows to downstream wetlands. During the Design Phase, all wetlands, streams and drainage channels within the project corridor will be delineated and a jurisdictional determination will be submitted to the USACE for concurrence and subsequent permitting. Typical stream tributary May 2013 11
Golden View Drive Elizabeth Street B B Rabbit Creek Road MOA Project #10-026 ³ Little Rabbit Creek B B B Ricky Road B D U East 156th Avenue B B Bridgeview Drive B D C C C C East 162nd Avenue East 164th Avenue D D B B B Ransom Ridge Road Prominence Pointe Drive D D D D D D C C East 172nd Avenue D D D D U D H Kallander Avenue P D D D D Bluebell Drive P P P D Romania Drive Legend P Bulgaria Drive Project Area A Potter Creek Stream P Wetlands & Designation Figure 4 - Wetlands Map Pre Final Design Study Report May 2013 12
F. Drainage Existing drainage facilities along Golden View Drive consist primarily of roadside ditches, channels, and culverts. A number of the ditches and open channels have been mapped by MOA Watershed Management Section (WMS) as drainage ways and are expected to be included under USACE jurisdiction. Based on visual inspection, the condition of these systems vary greatly. Many of the conveyance facilities have electrical heat trace installations including: heat trace in conduit mounted in culverts and structures, bare heat trace in culverts and ditches, and heat trace in conduit staked in ditches. Typical roadside ditch A segment of buried storm drain pipe runs along Golden View Drive from station 555+05 to station 564+21. A subdrain which runs from station 555+00 to station 558+30 is connected to this system, from there it is conveyed to just north of E. 164 th Avenue and discharged into an open channel. There are nine stream crossings along the project corridor, with existing culvert sizes varying from 18 to 72 inches in diameter. Seven of the streams are first order. One is second order; North Branch South Fork Little Rabbit Creek, and Little Rabbit Creek is third order. Third order streams are subject to higher scrutiny in regards to passing flows from larger flood events. Perched culvert at stream crossing May 2013 13
Stream Name Golden View Stream Crossings Crossing Station Catchment Area (Acres) Potter Branch 508+50 30 1 South Fork Little Survival Creek 522+15 36 1 South Branch Little Survival Creek 529+35 43 1 Little Survival Creek 535+70 357 1 North Branch Little Survival Creek 554+55 109 1 South Branch South Fork Little Rabbit Creek 570+05 192 1 North Branch South Fork Little Rabbit Creek 585+65 101 2 Little Rabbit Creek 595+60 4800 3 Elmore Creek 605+00 102 1 Order Drainage within the project area is influenced by steep grades, shallow bedrock, and shallow groundwater. Bedrock is as shallow as 2.5 feet in places, reducing space for groundwater to flow and effectively forcing it to the surface. There is a high incidence of groundwater seeps, particularly at cut banks for roads, ditches, and residences. These groundwater seeps are highly susceptible to freezing and icing problems in certain locations. The conditions described also result in substantial base flow in roadside ditches and drainages. Water that would have otherwise been subsurface is daylighted at road cuts, driveways, and ditches where it accumulates and flows over the ground. This intermittent groundwater contributes to a significant and typically steady base flow in many ditches, drainage ways, and small streams. Icing, also referred to as glaciation or aufeis, affects numerous locations along the project corridor. Typical locations are at driveway culvert crossings, roadway cut banks, and shallow-sloped, flat-bottom ditches. Severity of icing is variable and depends on a number of conditions, including: air temperature throughout the winter season, snow cover, wind, and depth of frost penetration. Typical Stream and culvert May 2013 14
Mid-winter thaw events typically exacerbate icing as daytime temperatures rise above freezing, creating runoff which later freezes at culverts and other constrictions created by roadway snow removal and storage. Many of the ditches and associated culverts are within the snow plow side-cast and snow storage area. The plowed snow is piled over culvert inlets, and even driven over by vehicles, creating a plugged-inlet condition when thaw events occur. Glaciation along Golden View Drive There are numerous private driveways that adjoin Golden View Drive. Crossing culverts are installed to maintain roadside-ditch connectivity. Many of these driveways culverts suffer from ineffective maintenance and have accumulations of sediment, vegetation and trash. Culverts with shallow cover and restricted inlets as described are very susceptible to icing. The existing storm drain system is shown in FIGURE 5. May 2013 15
Golden View Drive Elizabeth Street ELMORE CREEK Ricky Road Rabbit Creek Road East 156th Avenue MOA Project #10-026 ³ LITTLE RABBIT CREEK Bridgeview Drive NORTH BRANCH SOUTH FORK LITTLE RABBIT CREEK East 162nd Avenue East 164th Avenue SOUTH BRANCH SOUTH FORK LITTLE RABBIT CREEK Prominence Pointe Drive Ransom Ridge Road East 172nd Avenue NORTH BRANCH LITTLE SURVIVAL CREEK Kallander Avenue SOUTH FORK LITLE SURVIVAL CREEK Bluebell Drive SOUTH BRANCH LITTLE SURVIVAL CREEK LITTLE SURVIVAL CREEK Legend Stream Storm Pipe & Flow Direction POTTER BRANCH Romania Drive Bulg Culvert & Flow Direction Open Channel & Flow Direction Project Area Figure 5 - Existing Drainage Map Pre Final Design Study Report May 2013 16
G. Vegetation/Landscaping The majority of the existing vegetation along the project corridor is native birch and spruce forest. Cottonwoods and other riparian plants are found in the drainages. Overall, the vegetation has a natural, rural character indicative of the hillside area. The project corridor is dotted with driveway entries and mailboxes for private homes. There are some locations that have cluster-type mailboxes with the largest concentration located on the west side of Golden View Drive directly across from Moen Park. Typical vegetation along Golden View Drive There are two locations that have distinctly developed landscapes. The entry drive to Goldenview Middle School includes a large masonry entry sign surrounded by a maintained lawn. The edge of the lawn is lined with landscape boulders. Although this landscaped area is developed and maintained, it fits well into the overall rural appearance of the area. Further to the south lies the Prominence Pointe subdivision entry landscape. It has a formal Goldenview Middle School entry character and includes decorative fencing, an entry sign, a water feature, non-native ornamental landscape plantings, and a maintained lawn. This built landscape is distinctive within the overall rural appearance of the project corridor. May 2013 17
Prominence Pointe subdivision landscape Views from the roadway are limited due to the heavy mature vegetation. Some areas on the west side of the roadway, where the development of private homes has taken place, offer views of Turnagain Arm. H. Utilities Existing utilities within the project area include water, sanitary sewer, natural gas, electric, telephone, cable television, and fiber optic (See APPENDIX C for the location of the existing utilities). Many properties are served by private wells and septic systems. Utility locations are based on both utility company facility maps and field locates. Their locations are considered conceptual at this phase. A utility conflict report will be prepared during the design phase. Scoping letters have been sent to the utility companies requesting additional information on existing facilities and any plans for future upgrades. 1. Water The majority of the residences that front Golden View Drive are served by private wells. Private well locations have not been surveyed at this time but any impacts to private property caused by improvements to Golden View Drive will include researching the locations of existing wells for possible conflicts. Anchorage Water and Wastewater Utility (AWWU) also owns and operates water facilities within the Goldenview Park and the Prominence Pointe Subdivisions. A 12-inch ductile iron water main crosses Golden View Drive at E. 164 th Avenue (station 563+88). May 2013 18
AWWU intends to build a new water reservoir off of Golden View Drive just north of Romania Drive, on the west side of the roadway (on Parcel 172). This reservoir would be connected to the Prominence Pointe water system by a new 12-inch water main that parallels Golden View Drive. Expected construction date for the new water reservoir is unknown at this time. The current AWWU Water and Wastewater Master Plan maximum service area and the Hillside District Plan s proposed maximum service area are shown in FIGURE 6. The designated services areas limit the expansion of both public water and sewer systems on the hillside. AWWU was contacted for possible projects in the area. The 2012 AWWU Draft Water Master Plan has cited Golden View Drive as a possible corridor for future water main extension and AWWU has acquired a parcel for a future water storage tank at the southern end of Golden View Drive. Extending water services is in the long term forecast 10 to 20 years out. AWWU will also be evaluating the hydraulics of the possible proposed route along Golden View Drive and may choose a different alignment, not along Golden View Drive, that better meets the needs of the distribution system to serve south Anchorage. 2. Sewer The majority of the residences that front Golden View Drive are served by private septic systems. Private septic systems have not been surveyed at this time but any impacts to private property caused by improvements to Golden View Drive will include researching the locations of existing septic systems for possible conflicts. Anchorage Water and Wastewater Utility (AWWU) owns and operates the sanitary sewer facilities within the Goldenview Park and the Prominence Pointe Subdivisions. A 12-inch ductile iron sewer main crosses Golden View Drive at E. 164 th Avenue (station 563+60). A 12-inch ductile iron sewer main extends into Golden View Drive at Bridgeview Drive (station 576+85). May 2013 19
Figure 6 AWWU and HDP water and sewer service area boundary 3. Natural Gas ENSTAR Natural Gas Company owns and operates natural gas facilities within the project area. A 4-inch plastic gas main runs along the east side of Golden View Drive from Romania Drive (beginning of the project) north to E. 172 nd Avenue (station 536+80), May 2013 20
where it crosses to the west side of the road. This line continues north on the west side of the road to E. 164 th Avenue (station 563+60) where it crosses back to the east side of the road and continues to Rabbit Creek Road (end of the project). The 4-inch plastic line serves many of the residences and neighborhoods that front Golden View Drive. Approximately thirty steel and plastic service lines, ranging in size from 5/8 inch to 1 inch, are fed directly from the 4-inch plastic gas main. Additionally, 2- inch plastic gas mains connect to the 4-inch main at Bluebell Drive, Kallander Avenue, Ransom Ridge Road, E. 164 th Avenue, E. 162 nd Avenue, and E. 156 th Avenue. If roadway grade changes occur, it is likely that much of the 4-inch plastic gas main as well as the 2-inch gas crossings will Enstar's pressure reducing vault require adjustments. In addition to the 4-inch plastic gas main, Enstar also owns a 12-inch pressurized transmission main that runs along the east side of the Golden View Drive ROW from E. 172 nd Avenue (station 536+90) to Rabbit Creek Road (end of the project). A pressure reducing vault for this main is located on the southeast corner of the E. 172 nd Avenue and Golden View Drive intersection (station 536+75). Significant changes in grade over the transmission main will require adjustment of the pressurized main. Due to the importance of this main to the overall Enstar Natural gas system, interruption of this main should be avoided. 4. Electric Chugach Electric Association (CEA) owns and operates electrical facilities within the project area. CEA has existing 3 phase power lines that run the extent of the project on the east side of Golden View Drive. The power lines are overhead along Golden View Drive except in front of Prominence Pointe where they are underground. These lines provide power to the residences and neighborhoods that front Golden View Drive. Overhead electric lines cross Golden View Drive in twelve separate locations. Additionally, underground three phase lines and single phase lines cross Golden View May 2013 21
five times between E. 172 nd Avenue and E. 164 th Avenue. Underground lines also cross Golden View Drive at Rabbit Creek Road. Improvements to Golden View Drive that directly impact the overhead lines and poles, reduce minimum clearance requirements for overhead lines, or reduce minimum coverage requirements for underground power lines will require adjustments. 5. Telephone Alaska Communication Systems (ACS) and General Communications Inc. (GCI) own and operate telephone facilities, including lines and pedestals, in the project area. ACS owns three overhead telephone lines that run along the east side of Golden View Drive on CEA s utility poles. Similar to CEA, these telephone lines run underground in front of the Prominence Pointe Subdivision. A 600-pair underground telephone line runs along the west side of Golden View Drive from Romania Drive to station 524+13 (approximately 700 feet south of Bluebell Drive), where it crosses Golden View Drive and connects to the aerial system on the east side of the roadway. Underground telephone lines cross Golden View Drive at Romania Drive, Ransom Ridge Road, Prominence Pointe Drive, Ricky Road, and Rabbit Creek Road. Aerial telephone lines cross Golden View Drive approximately 500 feet south of Kallander Avenue, at E. 164 th Avenue, and at E. 162 nd Avenue. Adjustments to the telephone system will be required if improvements to Golden View Drive cause minimum clearances for underground and overhead telephone utilities to not be met. 6. Cable Television General Communications Inc. (GCI) also owns and operates cable TV facilities within the project area, consisting of underground coaxial cable lines, fiber optic lines, and pedestals. On the east side of Golden View Drive, a fiber optic lines runs from Romania Drive north to Prominence Pointe. Just north of Prominence Pointe Drive, the fiber optic line crosses Golden View Drive where it is joined by a second underground fiber optic line. The two underground fiber optic lines continue north along the west side of Golden View Drive to Rabbit Creek Road. May 2013 22
In addition to the fiber optic lines, GCI also has an underground 0.875 coaxial cable that runs along the east side of Golden View Drive from Romania Drive to Prominence Pointe Drive (station 560+38). From here, the coaxial cable crosses Golden View Drive and continues north to Rabbit Creek Road. The 0.875 coaxial cable has spur lines that cross Golden View Drive at Bridgeview Drive and approximately 600 feet south of Rabbit Creek Road. An underground 0.500 coaxial cable runs along the west side of Golden View Drive from Ransom Ridge Road to Goldenview Middle School and on the east side of Golden View Drive from Prominence Pointe to Rabbit Creek Road. An underground 0.625 coaxial cable runs along the east side of Golden View Drive between E. 162 nd Avenue and E. 156 th Avenue. A 0.625 coaxial cable also crosses Golden View Drive at Romania Drive. Adjustments to the cable system will be required if improvements to Golden View Drive cause conflicts with underground facilities. May 2013 23
III. Traffic and Safety Analysis A Traffic and Safety Analysis, dated February 17, 2012 was completed by Kinney Engineering for this project. A summary of the analysis is presented below and the complete report is included in APPENDIX D. A. Existing Traffic Volume & Speed Data Existing published traffic data, supplemented with new field data, was gathered to analyze existing traffic in the study area. This data included: Speed Studies Traffic Volume Data Intersection Turning Movement Counts Existing Traffic Volumes The ADOT reports the Average Annual Daily Traffic (AADT) by segment for major streets. The following table summarizes the AADT for the major streets in the project area: Table 1 Existing AADT Traffic Data Golden View Drive Segment 2010 AADT Bulgaria Drive to Rabbit Creek Road 2,210 North of Rabbit Creek Road (to E. 142 nd Street) 275 Rabbit Creek Road Segment 2010 AADT Elmore Road to Golden View Drive 7,130 Golden View Drive to Clark s Road 2,410 In addition to the ADOT data, the MOA and Kinney Engineering conducted both intersection and mid-block volume counts. Existing peak hour turning movement counts are shown on FIGURE 7. May 2013 24
Figure 7 Existing Peak Hour Turning Movement Counts May 2013 25
Many residents of Golden View Gate Subdivision have expressed that they experience cutthrough traffic on Bridgeview Drive between Golden View Drive and Rabbit Creek Road. As a result, volume and speed data was also collected for Bridgeview Drive; however, the traffic volume study does not support the presence of cut-through traffic. Traffic using Bridgeview Drive appears to be mostly parents of Goldenview Middle School students who drive their students to school. Bridgeview Drive Link Count Location Date EB or NB WB or SB Bridgeview Drive near Goldenview MS 9/23/11-9/27/11 184 (EB) 221 (WB) Bridgeview Drive near covered bridge 9/23/11-9/27/11 1,338 (NB) 1,242 (SB) Speed Studies The posted speed on Golden View Drive is 35 MPH. The results of speed studies taken on Golden View Drive and Bridgeview Drive between 2005 and 2011 are shown below. Location Table 2 Speed Study Results Golden View Drive NB 85% Date Speed (MPH) SB 85% Speed (MPH) 0.2 miles south of Bluebell Dr. 5/18/10 44 43 50 north of Prominence Pointe Dr. 4/21/10 45 47 At Goldenview MS driveway 9/22/11 46 46 South of Rabbit Creek Road 5/3/05 45 46 Bridgeview Drive Location Date NB 85% Speed (MPH) SB 85% Speed (MPH) Between Cape Seville & Golden View Dr. 8/10/05 34 35 Between Cape Seville & Noble Point 8/10/05 31 29 East end near Middle School 9/29/11 21 26 South of covered bridge 9/29/11 31 30 NB - Northbound SB Southbound May 2013 26
B. Traffic Projections The design year for this project is 2033. Future traffic volumes for 2033 were determined using the 2027 Anchorage Metropolitan Area Transportation Solutions (AMATS) model, modified to reflect the recommendations in the Hillside District Plan, and applying traffic growth based on expected population. Kinney Engineering also updated the traffic model by including recommendations from NCHRP Report 25 Highway Traffic Data for Urbanized Area Project Planning and Design, adding Goldenview Middle School as a special generator, and refining the road centerlines and minor street accesses to Golden View Drive. The 2025 Long Range Transportation Plan for the MOA includes a long range project that would extend Golden View Drive to Potter Valley Road. There is uncertainty regarding whether this project would be constructed prior to the 2033 design year; therefore, the model was developed and run in two scenarios with and without the Potter Valley Road connection. FIGURE 8 shows the projected 2033 AADTs both with the Potter Valley Road extension and without the Potter Valley Road extension. Projected peak hour turning movements for major intersections on Golden View Drive are shown on FIGURE 9. May 2013 27
Figure 8 Projected AADT (design year 2033) May 2013 28
Figure 9 Projected Peak Hour Turning Movement Counts May 2013 29
C. Traffic Characteristics Traffic characteristics vary along Golden View Drive due to the school and more densely developed northern section versus the more rural section of the southern end. Therefore, traffic characteristics for Golden View Drive were analyzed in two separate segments: Segment 1 Bulgaria Drive to Bluebell Drive and Segment 2 Bluebell Drive to Rabbit Creek Road. Traffic characteristics are summarized in the table below. 2033 Design Year Traffic Characteristic Summary Traffic Characteristic Bulgaria Drive to Bluebell Drive Bluebell Drive to Rabbit Creek Road Design Hour Volume 10% 10% Peak Hour Factor (AM and PM) 0.95 0.95 Peak Hour Factor (AM Peak-NB left turn movement at Rabbit Creek Intersection) -- 0.70 Directional Distribution (North/South) 30/70 35/65 Heavy Vehicle Percentage (AM Peak) 2.0% 5.0% Heavy Vehicle Percentage (PM Peak) 2.0% 2.0% Equivalent Single Axle Loads 19,000 390,000 Design hour volume is used for capacity and equivalent single axle load computations for roadway sections. The design hour volume was estimated using the 30 th Highest Hour of the closest permanent traffic recorder, located on O Malley Road. A design hour volume of 10.0 percent should be used for all segments on Golden View Drive. Peak Hour Factors (PHF) are a measure of the uniformity of the traffic and used to convert volumes to 15 minute design flow rates for capacity analyses. As the peak hour factor approaches 1.00, the traffic becomes more uniform. A peak hour factor of 0.95 was assumed for all movement during both the AM and PM peak periods with the exception of the AM northbound left turn movement at the intersection of Rabbit Creek Road and Golden View Drive. This movement experiences a high AM peak corresponding to the Goldenview Middle School peak. A peak hour factor of 0.70 was used for this movement. Directional distribution was estimated using the link counts for the peak hour of traffic. Traffic counts showed the daily peak hour was from 5:00 to 6:00 PM. The directional distributions during the peak hour are 35/65 for the segment between Rabbit Creek Road and Bluebell Drive and 30/70 for the segment from Bluebell Drive to Bulgaria Drive. May 2013 30
The heavy vehicle percentage is the percent of the AADT that is made up of heavy vehicles. The turning movement field data was used to calculate the peak hour heavy vehicle percentage. A heavy vehicle percentage of 2.0 percent was used for both segments except in during the AM peak hour between Rabbit Creek Road and Bluebell Drive. This segment is influenced by the large number of school buses and a heavy vehicle percentage of 5.0 percent was used. D. Crash Data Crash records have been obtained for the most recent 10 years (1999 2008). A total of 71 crashes occurred in the project area during that time period (see APPENDIX D). Nearly all the crashes (66 out of 71) recorded on Golden View Drive were located at intersections. Intersection crash rates were determined for each major intersection. The upper control limit (UCL), or critical rate, is determined statistically as a function of the statewide average crash rate. Locations with rates that exceed the UCL are inferred to be well above the average and are not likely due to chance. TABLE 3 below summarizes the intersection crashes and UCLs along Golden View Drive from 1999 2008. Crash diagrams are summarized in APPENDIX D. Table 3 1999-2008 Crash Summary for Intersections on Golden View Drive Intersection: Golden View Drive at... Total Crashes (1999-2008) Crashes/ MEV Control State Average (1999-2008) UCL @ 95.00% Confidence at Romania Dr. 3 0.374 Stop (3 leg) 0.535 1.022 at Bluebell Dr. 12 1.364 Stop (3 leg) 0.535 0.997 at E. 172 nd Ave. 4 0.528 Stop (3 leg) 0.535 1.038 at Ransom Ridge Rd. 4 0.546 Stop (3 leg) 0.535 1.048 at Prominence Pointe Dr. 2 0.202 Stop (3 leg) 0.535 0.968 at E. 162 nd Ave. 3 0.312 Stop (4 leg) 0.669 1.155 at Bridgeview Dr. 6 0.764 Stop (3 leg) 0.535 1.028 at E. 156 th Ave. 5 0.680 Stop (4 leg) 0.669 1.233 at Rabbit Creek Rd. 27 1.278 Stop (4 leg) 0.669 0.985 Legend: = Above Critical Rate May 2013 31
Two intersections, Bluebell Drive and Rabbit Creek Road, have crash rates that are higher than the statewide average and higher than the critical rate for similar intersections. Crash diagrams for these intersections can be found in APPENDIX D. Right angle crashes account for 48 percent of the crashes at the Golden View Drive and Rabbit Creek Road intersection. Severity of the crashes at this intersection are not statistically above the statewide average rate. Nearly 60 percent of the crashes occurred during the winter with almost 48 percent of them occurring during the Goldenview Middle School peak periods. Northbound movements caused 56 percent of crashes at the Rabbit Creek Road intersection. The high rate of crashes for the northbound movement can be partially attributed to the poor level of service during the AM peak hour. Improvements to this intersection should include mitigation measures to address the large number of right angle crashes. Of the twelve reported crashes at Bluebell Drive, seven (58 percent) were right angle crashes. All but one of these crashes occurred under either snow or ice roadway surface conditions. These crashes may be partially attributed to the steep grade on Bluebell Drive. E. Operational Analysis 1. Segment Analysis Golden View Drive Golden View Drive between Rabbit Creek Road and Romania Drive is currently a two-lane facility. Except for the two-way stop at Rabbit Creek Road, Golden View Drive traffic is under an uninterrupted traffic flow regime between Rabbit Creek Road and Romania Drive. The two-lane highway methodology from the 2010 Highway Golden View Drive at morning peak Capacity Manual was used for capacity analysis. During the 2033 design year, Golden View Drive between Romania Drive and Bluebell Drive will operate under a level-of-service (LOS) B, with or without the Potter Valley Road connection. Golden View Drive between Bluebell Drive and Rabbit Creek Road will operate under a LOS C, with or without the Potter Valley Road connection. A two-lane section will be adequate for achieving acceptable levels of service through the design year. May 2013 32
2. Intersection Analysis A capacity analysis for the intersections of Golden View Drive with roads designated as major or secondary (Prominence Pointe Drive, E. 156 th Avenue, and Rabbit Creek Road) was performed using the 2010 Highway Capacity Manual. Intersection performance is measured by the average vehicle delay, which relates to the LOS, during the most critical operational time periods (in this case, AM and PM peak hours). The following tables summarize the results of this analysis. Golden View Drive at morning peak Table 4 Golden View at E. 156th & Prominence Pointe Operational Analysis Approach WB L/T/R EB L/T/R Golden View Drive @ E. 156th Avenue Existing Configuration 2011 AM Peak Level-of-Service B C 2011 PM Peak Level-of-Service A A 2033 AM Peak Level-of-Service B C 2033 PM Peak Level-of-Service B D Golden View Drive @ Prominence Pointe Drive Existing Configuration 2011 AM Peak Level-of-Service A - 2011 PM Peak Level-of-Service A - 2033 AM Peak Level-of-Service A - 2033 PM Peak Level-of-Service A - NB - Northbound SB - Southbound WB - Westbound EB - Eastbound L - Left T - Through R Right May 2013 33
F. Side Street Intersections/Access Control Most of the developed side streets intersect Golden View Drive at a tee. Two side streets intersect with Golden View Drive at a four-way intersection: Ricky Road/E. 156 th Avenue and E. 162 nd Avenue. The following side streets connect with Golden View Drive on the east side: Romania Drive Bluebell Drive Prominence Pointe Drive E. 162 nd Avenue E. 156 th Avenue (Ricky Road on the west side of Golden View) Side streets connecting to the west side include: Kallander Avenue E. 172 nd Avenue Ransom Ridge Road E. 164 th Avenue E. 162 nd Avenue Bridgeview Drive Ricky Road (E. 156 th Avenue on the east side of Golden View) These side streets are all stop-controlled intersections with the primary movement on Golden View Drive (north-south traffic) and the stop-controlled secondary movement on the side street (east-west traffic). Traffic volumes along the side streets are well below the requirement for the addition of turn lanes on the side street or Golden View Drive. There are 29 private driveways that have direct access onto Golden View Drive. These driveways vary in width and typically have either asphalt or gravel surfacing. Many driveways have steep grades exceeding 10 percent. IV. Stakeholder/Public Involvement An Open House was held on May 16 th, 2011 to introduce the project and receive input from stakeholders. Approximately 40 stakeholders attended the meeting. An Advisory Committee was then established in December 2011 and met on January 11, 2012 to provide input on the preliminary draft alternatives for Golden View Drive and the Rabbit Creek Road Intersection prior to the second public Open House. The second public Open House was held on January 26, 2012 to present the draft alternatives and a summary of the Draft DSR. The meeting was advertised through direct mailing, electronic newsletters, and on the web page. Over 52 stakeholders attended the meeting. The Planning and Zoning Commission also held a public hearing on the Draft DSR on July 2, 2012. A member of the project team regularly attends the May 2013 34
Rabbit Creek Community Council meetings and a special meeting was held with the board members and the MOA to discuss lighting and the posted speed limit on February 27, 2013. In general, stakeholders are well-educated about the project constraints including steep slopes and drainage. Stakeholders generally support only one pedestrian facility along Open House #1 (May 2011) Golden View Drive in order to minimize impacts to adjacent property owners and wetlands. Stakeholders have not reached consensus on street lighting and the posted speed limit. Conceptual alternatives for improving Rabbit Creek Road intersection were evaluated and presented to the public; however, it was explained that intersection improvements are currently on-hold pending completion of a future ADOT study of multiple the hillside intersections, including the intersection of Rabbit Creek Road and Golden View Drive. Improvements to the intersection of Rabbit Creek Road/Golden View Drive will be dependent on the results of the hillside intersection study and prioritization of all hillside intersections by ADOT. Comments received to date can be found in APPENDIX A. The CSS process will continue throughout the design phase of the project with additional opportunities for stakeholders to obtain information and provide feedback through the web page, e- newsletter updates, open houses, community council presentations, and direct feedback through phone calls and e-mail. The Advisory Committee will also continue to meet as necessary to provide input to the project team. Open house #2 (Jan 2012) May 2013 35
V. Design Criteria A. Design Standards Project design criteria are a function of the roadway characteristics and the design standards used. The owner of the facility and the funding source often dictate the design standards that are used. The current funding source for the improvements is through the State of Alaska. Future funding is likely to be a combination of local road bonds and state grants. Rabbit Creek Road is owned and maintained by ADOT and Golden View Drive is owned and maintained by the MOA; therefore, the design criteria for the intersection is based on both MOA and ADOT design standards. The documents listed on the right provide the design guidance, standards and requirements for this project. TABLE 5 provides a listing of the design criteria recommended for the proposed roadway and pathway improvements. Design variances are required for recommended solutions that do not meet the requirements of the MOA Design Criteria Manual (DCM). May 2013 36
1. Municipality of Anchorage The Official Streets and Highways Plan (OS&HP) is currently the planning document providing policies and standards for the transportation needs within the MOA. The OS&HP lists the functional classification for primary roadways located within Anchorage, Eagle River and Girdwood based on the Long-Range Transportation Plan. The OS&HP provides general roadway design standards based on functional classification including the number of lanes, width of ROW, and distance between intersections. Golden View Drive south of Rabbit Creek Road is designated as a Collector and north of Rabbit Creek Road, it is a Neighborhood Collector. Rabbit Creek Road west of Golden View Drive is classified as a Class II Minor Arterial and a Collector to the east. FIGURE 3 shows the roadway classifications in the project vicinity. The MOA PM&E Design Criteria Manual (DCM) is an implementation document and provides detailed design criteria for roadways developed within the MOA using local or state funds. The design standards are based on the functional classifications included in the OS&HP. Design variances are required for recommended solutions that do not meet the DCM design criteria. 2. State of Alaska The ADOT Highway Preconstruction Manual (PCM) provides detailed design criteria for federally-funded roadway projects within the State of Alaska. The PCM is intended to interpret and amend the goals and objectives of the AASHTO Policy on Geometric Design of Highways and Streets, the Green Book, (AASHTOGB). The PCM references other documents, including AASHTOGB, for many design parameters including alignment, intersection design, sight distance, design speed, grades, lane width and shoulder width. 3. Federal AASHTOGB is a comprehensive reference manual for planning and design of highways and streets in the United States. The most current publication year for the AASHTOGB is 2011. The manual provides roadway design recommendations and standards based on functional classification. May 2013 37
B. Design and Posted Speed The design speed affects the length of sight distance available along the roadway s horizontal alignment and vertical profile, particularly at intersecting roadways and pedestrian facilities. As design speeds increase, longer sight distances are required to provide more reaction time and braking distance to respond to roadway obstacles. Additionally, higher design speeds require a more gradual change in horizontal and vertical alignment which typically increases the extent of cut and/or fill near hills. It is important that the design speed is slightly higher than the posted speed (typically 5 to 10 MPH higher) to provide a margin of safety for drivers driving at the speed limit in unfavorable conditions such as poor weather. Golden View Drive has a posted speed of 35 MPH. The DCM requires a design speed of 45 MPH for residential collectors. Rabbit Creek Road has a posted speed of 45 MPH. The PCM references the AASHTOGB for posted and design speed which recommends a design speed of 40 to 50 MPH for rural arterials in mountainous terrain. Since the posted speed is already within the recommended design speeds, a design speed of 55 MPH was chosen for Rabbit Creek Road 85% west of Golden View Drive. East of Golden View Drive, where Rabbit SPEED Creek Road is a collector, the AASHTOGB recommends a design speed 46 of 40 MPH in mountainous terrain. This recommended design speed is below the existing posted speed and thus a design speed of 50 MPH was chosen for Rabbit Creek Road east of Golden View Drive. The 85 th percentile speed along Golden View Drive is approximately 46 MPH. Raising the posted speed to more closely match the existing 85 th percentile speed has proven to be an effective method to reduce the variation between average speed and 85 th percentile speed. Reducing speed variation results in safer driving conditions. Studies have also shown that an increase in posted speed does not have an equal increase in average travel speed. In December 2011, a memorandum was submitted to the MOA Traffic Engineering Division to obtain their input on the posted speed along Golden View Drive. Recommendations from the Traffic Division were requested in regards to raising the posted speed to 40 MPH or maintaining the existing posted speed of 35 MPH. The Traffic Division recommends raising the speed limit to 40 MPH. May 2013 38
School Speed Zone: With the proposed pedestrian improvements and improved street lighting (see SECTION VI. DESIGN ALTERNATIVES, E. PEDESTRIAN FACILITIES), a safe walking route to school may be established along all or portions of Golden View Drive. Further analysis and coordination with the Anchorage School District will be conducted during the design phase for possible safe walking routes to school. If a walking route is established along portions of Golden View Drive, a 20 MPH speed school zone for Goldenview Middle School area may also be warranted. C. Accessibility Guidelines The currently adopted requirements for accessibility in the MOA are based on the Americans with Disabilities Act (ADA). The project uses ADA guidelines as minimum criteria, but also incorporates the Access Board s Proposed Accessibility Guidelines for Pedestrians in the Public Right-of-Way (July 2011). To be compliant with ADA, pedestrian facilities shall have a maximum cross slope of 2 percent, a maximum vertical step of one-quarter inch, a minimum vertical clearance of 80 inches, a maximum sustained running slope of 5 percent, or equal to the road grade if paralleling the roadway, and a maximum curb ramp slope of 8.33 percent. D. Typical Section The typical lane width for a residential collector street is between 11 and 12 feet depending on existing and forecasted neighborhood densities, zoning, and traffic volumes. Shoulder widths vary between 3.5 and 5 feet on residential collectors. Per the DCM, pedestrian improvements are to be provided on both sides of a collector street. Pathways and sidewalks are typically separated from the roadway to provide pedestrian comfort and safety, increase intersection sight distances, and provide room for snow storage. Snow storage area is required by Anchorage Municipal Code 21.80.330: All street rights-of-way shall include an open area, which may contain sidewalks, for snow storage. The open area (buffer) shall extend 7-feet outward from the back of the curb. Having the grass buffer behind the curb becomes even more important when using a narrow 3.5 foot (or less) shoulder cross section. This narrower shoulder provides little room for snow storage on the street, and snow will need to be temporarily placed behind the curb. Lack of an adequate grass buffer could mean pedestrian passage is blocked partially or completely during major snow events. May 2013 39
E. Clear Zone The DCM requires a minimum horizontal clearance to obstructions of 1.5 feet beyond the face of curb in urban conditions. In rural conditions where there is no curb, the DCM does not directly address clear zone requirements but requires adherence to AASHTOGB. The AASHTOGB references AASHTO s Roadside Design Guide (RDG) which defines the clear zone as the area outside of the traveled way, including the shoulder, which will be available for recovery by errant vehicles. The recommended clear zone width is a function of the design speed, traffic volume, functional classification of the roadway, and the side slope of the area. The clear zone required for a freeway-type rural roadway with a design speed of 45 MPH and an ADT of 1,500 to 6,000 is 16 to 18 feet, with a fore slope of 1V:6H or flatter. However, the AASHTOGB, similar to the DCM, recognizes the impracticability of constructing a full clear zone, in accordance with the RDG, in urban areas. Where establishing a full-width clear zone in an urban area is not practical due to right-of-way constraints, consideration should be given to establishing a reduced clear zone or incorporating as many clear zone concepts a practical, such as removing roadside objects or making them crashworthy. F. Lighting The Hillside District Plan (HDP) classifies Golden View Drive as an Urban Roadway within ARDSA and directs designers to the MOA Design Criteria Manual (DCM) for applicable design standards. The DCM (Section 5.3.A) states lighting requirements are based primarily on the type of facility and volume of use. Golden View Drive is classified by the MOA Official Streets and Highways Plan as a collector roadway. When installed, lighting systems shall be designed to the DCM s Chapter 5 criteria, enhancing traffic and pedestrian safety. A properly designed lighting system will: Provide the minimum maintained average luminance and illuminance levels specified for roadways, sidewalks, and intersections. Provide a uniformity of lighting that does not exceed the maximum ratios specified for roadways, sidewalks, and intersections. Minimize construction and maintenance costs. Avoid adverse impacts to adjacent properties. Reveal hazards to pedestrians and vehicular traffic. May 2013 40
The MOA has begun retrofitting existing luminaire poles with luminaires that use light emitting diodes (LEDs) as the light source. They have requested new lighting systems also use LED luminaires that produce light with a 4300K correlated color temperature (CCT), the equivalent of sunlight. The new proposed LED lighting system is to be designed to provide the light levels specified in the DCM. The luminaires should also provide a full cutoff light distribution to reduce the negative effects of casting light on nearby properties (especially residences) and illuminating the night sky. To minimize the trespass of light on adjacent properties and reduce glare, luminaires are to be installed approximately 30 feet above the pavement on collector roadways. G. Landscaping In accordance with Chapter 3 of the DCM, landscaping efforts for collector streets should provide plantings that integrate new improvements with those of adjacent residential properties to provide an attractive transition between the street and the buildings. A 7-foot separation is desired between back of curb and the pathway or sidewalk to provide for temporary snow storage and to keep the facilities clear of snow. The grass buffer will also help treat runoff during periods that it is not used for snow storage. Landscaping should be placed to the outside edge of the ROW adjacent to the property lines to take advantage of landscape improvements in the front yard setbacks. Within Chapter 2 of the Hillside District Plan, the following goals relate to the appearance of the landscape for this project: Goal 5. Environmental Quality: Protect environmental quality on the Hillside, including: providing corridors for drainage, protecting natural systems such as aquifer recharge areas and stream corridors, protecting wildlife travel corridors and habitat, and providing open space for views and recreation. Goal 6. Parks and Open Spaces: Maintain, supplement and enhance a system of parks, trails, open spaces and other active and passive recreation areas. May 2013 41
Goal 7. Visual Quality: Protect views, both looking out from the Hillside and views of the Hillside as seen from the rest of Anchorage (for example, by maintaining vegetation, limiting cut-and-fill, and guiding the location and character of new residential development). May 2013 42
H. Design Criteria Summary Table 5 Design Criteria Summary CRITERIA Design Standard Value Reference Functional Classification Collector OS&HP AADT 2010 2,210 vpd Field Data Traffic AADT 2030 11,199 vpd Modeling Data Design Vehicle WB-50 DCM 6.4 B Design Speed 45 MPH DCM Table 1-4 Posted Speed 40 MPH MOA Traffic Division Horizontal Curve Radius, AASHTOGB, 1,039 ft Horizontal Minimum, No Super-elevation Table 3-13b Alignment Stopping Sight Distance, Min 360 ft DCM 1.9.D Clear Sight Triangle Length 500 ft DCM Figure 1-19 Vertical Grade, Maximum 10.0% (hillside) DCM 1.9.D Vertical Vertical Curve K-Values, Min Alignment Crest Curve 61 DCM Figure 1-16 Sag Curve 79 DCM Figure 1-17 Number of Lanes 2 OS&HP Lane Width 11 ft DCM Figure 1-11 Cross Shoulder Width 3.5 5.0 ft DCM Table 1-4 Section Curb & Gutter Type 1 DCM Figure 1-11 Side slopes 2:1 maximum DCM 1.9.D.5 Clear Zone 1.5 ft DCM 1.9.E.5 Pathway requirements Both sides of roadway DCM Figure 1-11 Sidewalk Width 5.0 ft DCM Table 1-4 Miscellan- Pathway Width 8.0 ft DCM Table 1-4 eous Separation from Back of Curb 0.0 7.0 ft DCM Table 1-4 Maximum driveway width, up to 7-plex 14.0 20.0 ft 28.0 ft allowed with restrictions DCM Appendix 1D Maximum driveway grade ± 10% DCM Appendix 1D Pedestrian Conflict Areas Low DCM 5.4.B Lighting Maximum Veiling Luminance Ratio 0.4 DCM Table 5-1 Minimum Illumination Level 0.6 fc DCM Table 5-1 Maximum Uniformity Ratio 4:1 DCM Table 5-1 DCM = Municipality of Anchorage s Design Criteria Manual OS&HP = Official Streets and Highways Plan AASHTOGB = American Association of State Highway and Transportation Officials Geometric Design of Highways and Streets ( Green Book ) May 2013 43
VI. Design Alternatives A. Design Challenges Some of the significant design challenges associated with Golden View Drive, the intersecting side streets, driveways, and the intersection with Rabbit Creek Road include: Golden View Drive Golden View Drive is within ARSDA. East and west of Golden View Drive, roads and associated drainage ditches are located in and maintained by private subdivisions or the South Goldenview Area RRSA. No single entity is responsible for managing the watershed and limited resources result in an uncoordinated approach. Golden View Drive is a narrow roadway with steep surrounding terrain (generally uphill to the east and downhill to the west). Side streets have steep grades with little or no landings. Many side street grades exceed 10 percent. Numerous driveways are located on Golden View Drive, a collector road. Driveways have steep existing grades with little or no landings. The streams and drainage ways along the east side of Golden View Drive must be maintained in accordance with permitting requirements. Challenges along Golden View Drive: steep adjacent terrain, driveways, and side streets Balancing the need for mobility with the rural feel of the neighborhood. May 2013 44
B. Golden View Drive Alignment and Profile A proposed roadway alignment that follows or parallels the existing roadway provides the least impact. It minimizes ROW requirements and impacts to existing development or vegetation. Below are relevant excerpts of the roadway design criteria from the DCM: Street Grades (Section 1.9.D.2) For streets or roads in Hillside areas with 2,000 or greater projected Average Daily Traffic (ADT), the maximum road grade is 8.0 percent. For streets or roads in Hillside areas with less than 2,000 projected ADT, the maximum road grade is 10.0 percent. o An occasional road grade between 10.0 percent and 12.0 percent may be allowed on short, straight sections not exceeding 250 feet. o A minimum 500-foot straight section of roadway shall not exceed 10.0 percent above and below the road grades exceeding 10.0 percent. o Grades exceeding 10.0 percent are not permitted within 150 feet of intersection centerlines. The maximum grade of a primary street through an intersection is 5.0percent. Horizontal Design Standards (Section 1.9E) Minimum horizontal curve radius for a secondary street is 150 feet. Note: A Design Variances Memo has been submitted to MOA PM&E under separate cover for those items requiring variances from the DCM standards. 1. Golden View Drive Profile The proposed Golden View Drive profile is based on a design speed of 45 MPH, in accordance with the DCM for a residential collector. This roadway profile generally follows the existing roadway profile but varies higher or lower than the existing ground to minimize impacts to adjacent properties, side streets, and driveways. See APPENDIX B for preliminary roadway plan and profile sheets. A preliminary analysis of the Golden View profile resulted in the following recommendations: May 2013 45
Raise the roadway profile near Romania Drive to reduce impacts to the steep grade of Romania Drive. Lower the roadway profile near Ransom Ridge Road to reduce impacts to the steep grade of Ransom Ridge Road but keep the roadway profile generally at existing grade near Prominence Pointe Drive to reduce impacts to Prominence Pointe Drive. Raise the roadway profile near Bluebell Drive but keep the profile as low as possible near Parcel 168 to reduce impacts to the adjacent steep side street and driveways. Reduce the roadway grade between Ransom Ridge Road and E. 172 nd Avenue to 10.0 percent (see paragraph below). The existing grade on Golden View Drive between Ransom Ridge Road and E. 172 nd Avenue is 11.6 percent with steep surrounding terrain. The proposed roadway grade for this location is 10.0 percent. Even with the roadway grade reduced from 11.6 percent to 10.0 percent, retaining walls would still be required along this area. A variance would be required for this grade because it is greater than 8.0 percent with a projected ADT greater than 2,000. The proposed grade of 10.0 percent is the best balance between reducing the existing steep roadway grade and minimizing impacts to adjacent properties and therefore, a roadway grade of 10.0 percent at this location is recommended. Steep existing grade of Golden View Drive (11.6%), south of Ransom Ridge Road May 2013 46
2. Golden View Drive Profile at Bluebell Drive: Golden View Drive near Bluebell Drive is bordered by steep uphill grades to the east and steep downhill grades to the west. Bluebell Drive intersects Golden View Drive at station 531+00 on the east while the driveway to access Parcel 167 is centered at station 531+18 on the west. The existing grade on Bluebell Drive is 14.6 percent (uphill away from Golden View Drive) while the existing grade on the driveway to Parcel 167 is -15.2 percent (downhill away from Golden View Drive). The driveway to access Parcel 168 is also in close proximity to the intersection with Bluebell Drive at station 528+58 and has an existing grade of -19.9 percent. Golden View Drive at Bluebell Drive. Steep uphill grades to the east (right side of photo); steep downhill grades to the west (left side). A separate project was initiated with funding from a state grant to address the steep grades on Bluebell Drive (MOA Project #08-016). Kinney Engineering, LLC was contracted to provide professional engineering services for the Bluebell Drive project. Kinney Engineering submitted a Draft Design Study Memorandum in September 2009 investigating various alternatives for Bluebell Drive. An updated Bluebell Drive Revised Design Study Memorandum was submitted in November 2012 (see APPENDIX H). The Golden View Drive project team has been coordinating with Kinney Engineering to efficiently and effectively design Golden View Drive at Bluebell Drive. The alternatives discussed below focus on options for Golden View Drive and the associated impacts to May 2013 47
Bluebell Drive; the detailed discussion of Bluebell Drive alternatives can be found in APPENDIX H. Preliminary engineering found the following alternatives for Golden View Drive at Bluebell Drive: Alt 1: Raise the roadway profile of Golden View Drive at Bluebell Drive by approximately 1.5 feet Alt 2: Follow the existing roadway profile of Golden View Drive near Bluebell Drive and then re-grade Bluebell Drive as necessary Alt 3: Split the roadway profile of Golden View Drive a. Alt 1: Raise Golden View Drive: The existing roadway profile of Golden View Drive near Bluebell Drive already contains a short, vertical curve, raising the roadway higher than the existing profile north and south of Bluebell Drive. Raising the profile of Golden View Drive at the intersection with Bluebell by approximately 1.5 additional feet above the existing elevation would allow the grades on Bluebell Drive to include a landing while not making the roadway grades steeper. Bluebell Drive could be graded at 14.3% with a 30.5-foot landing at 4% maximum grade. Improvements along Bluebell Drive would terminate (i.e. match existing grades) approximately 475 feet east from the centerline of Golden View Drive. Parcel 106 is located on Bluebell Drive, immediately east of the intersection with Golden View Drive, and has a loop-style driveway. Raising the profile of Golden View Drive near Bluebell Drive allows one of the two driveway entrances to have a grade less than 10%. The west and east driveway entrances would be graded at 18.7% and 8.2% respectively. Bluebell Drive May 2013 48
However, there are significant grading impacts on the steep downhill (west) side of Golden View Drive with this alternative. Approximately 180 linear feet of retaining wall would be required along Parcel 168. In addition, the driveway to Parcel 168 would need to be relocated to Kallander Avenue, requiring an address change. The driveway to Parcel 105B would not be impacted with this alternative. The intersection of Golden View Drive with Kallander Avenue is Driveway to Parcel 168 approximately 250 feet north of the intersection with Bluebell Drive. Raising the roadway profile to accommodate Bluebell Drive s grade also raises the profile at Kallander Avenue by approximately 2.5 feet (due to the lengthened vertical curves to accommodate sight distance). Kallander Avenue is currently steep (-10.4%) with no landing. With Alt 1, Kallander can be graded at -9.4% with a 40.5-foot landing at -3% maximum grade. However, there are significant grading impacts onto adjacent properties and the driveways to Parcels 166 and 166B would be impacted. Improvements extend along Kallander Avenue for approximately 370 feet west from the centerline of Golden View Drive. The property owners of Parcels 167 and 168 have been contacted to discuss options to mitigate the impacts to their driveways and properties. An on-site meeting was held with the owners of Parcel 167 to discuss alternatives and an on-site meeting is planned for later in the summer with the owners of Parcel 168. A comparison table of the impacts associated with Alts 1 and 2 for Golden View Drive near Bluebell Drive can be found on page 53. May 2013 49
b. Alt 2: Maintain Existing Roadway Profile of Golden View Drive Alt 2 investigated the option of not raising the roadway elevation of Golden View Drive near Bluebell Drive. With Alt 2, the vertical profile of Golden View Drive mostly follows the existing roadway profile. The vertical curves are lengthened in order to allow for proper sight distance. With Alt 2, Bluebell Drive could be graded at 15.0% with a 33-foot landing at 4% maximum grade. Improvements along Bluebell Drive would terminate (i.e. match existing grades) approximately 472 feet east from the centerline of Golden View Drive. Bluebell could also be graded at 14.3% (with a 30.5-foot landing at 4% grade), which extends the improvements approximately 515 feet east from the centerline of Golden View Drive. Assuming a grade of 14.3% along Bluebell Drive, the west and east driveway entrances to Parcel 106 would be graded at 23.0% and 11.9% respectively with Alt 2. Reconfiguring this driveway to achieve lesser grades may be required. Additionally, the driveway to Parcel 105B would be impacted with this alternative. The driveway to Parcel 105B has a current grade of 12.5% and would be graded at 11.6% with Alt 2. Approximately 160 linear feet of retaining wall would be required along Parcel 168 with Alt 2. The existing grade on the driveway to Parcel 168 is -19.9%; the proposed grade with Alt 2 is -25.7%, which would still require relocation to Kallander Avenue. Following the existing roadway profile of Golden View Drive near Bluebell Drive allows the elevation at Kallander Avenue to only be increased by 1-foot (again, due to the increased vertical curve lengths). Kallander can be graded at -8.5% with a 35.5-foot landing at -3% maximum grade. There are still grading impacts onto adjacent properties; however, they are less than with Alt 1. The driveways to Parcels 166 and 166B are still impacted, though not quite as severely as with Alt 1. To achieve the lesser grade along Kallander Avenue, improvements still extend for approximately 370 feet west from the centerline of Golden View Drive. May 2013 50
Impacts with Alt 1 and Alt 2 Golden View profile near Bluebell Drive Impact Retaining wall along Parcel 168 Existing Conditions Parcel 168 driveway -19.9% Alt 1 (raise Golden View near Bluebell) Alt 2 (maintain existing profile along Golden View) none 180 linear feet 160 linear feet -29.2% (relocate to Kallander Ave.) -25.7% (relocate to Kallander Ave.) Parcel 167 driveway -15.2% -16.4% -14.5% Bluebell Drive grade 14.6% Parcel 106 driveways (west, east) Kallander Avenue grade 2.5% -5.2% 14.3% (for 475 ft) 18.7% 8.2% 14.3% (for 515 ft) 23.0% 11.9% -10.4% -9.4% -8.5% Parcel 166 driveway -0.3% -10.4% -8.5% Parcel 166B driveway -5.6% -11.0% -10.4% c. Profile Split at Bluebell To better accommodate the steep uphill grades directly across from the steep downhill grades, splitting the roadway profile of Golden View Drive near Bluebell Drive was also investigated (Alt 3). The northbound (east) lane would follow a separate profile than the southbound (west) lane. The east lane would be higher than the west lane and separated by a curbed median with appropriate barrier fences and crash protection. The maximum elevation difference between the east and west lanes would be approximately 4.8 feet. The roadway profile split would begin at station 527+37 and end at station 533+52 (see FIGURE 10.) May 2013 51
Figure 10 Roadway profile split at Bluebell Drive Due to the extremely steep roadway grades on Bluebell Drive, the proposed curbline was maintained on the east side. This shifted the overall roadway section west. The additional width required for a median to accommodate the profile split results in downhill fill limits (on the west) that are actually greater than if the roadway profile were not split and results in a steeper driveway grade for Parcel 168. Below is a summary of the impacts with and without splitting the roadway profile of Golden View Drive near Bluebell Drive. May 2013 52
Impact Retaining wall along Parcel 168 Impacts with and without Golden View Roadway Profile Split Existing Conditions Parcel 168 driveway -19.9% (Alt 1) Without profile split Alt 3 (split profile grade) none 180 linear feet 260 linear feet -29.2% (relocate to Kallander Ave.) -32.6% (relocate to Kallander Ave.) Parcel 167 driveway -16.4% -16.4% -12.9% Bluebell Drive grade 14.6% 14.3% 14.1% In addition to the impacts on adjacent properties, a median would prevent left turns to and from Bluebell Drive and the adjacent properties. Vehicles travelling southbound wanting to access Bluebell Drive or vehicles exiting Parcels 167 and 168 and wanting to head north, would need to make a u-turn on Golden View Drive. A u- turn location would need to be provided south of the median. Splitting the roadway grade of Golden View Drive at Bluebell Drive was intended to reduce the impacts to the steep downhill driveways on the west side of Golden View Drive without making the steep uphill grade of Bluebell Drive worse. As this was not universally accomplished due to the extra width required for a median, it is not recommended. Based on preliminary analysis, Alternative 2 does not provide significant advantages over Alternative 1: a retaining wall along Parcel 168 is still required, Parcel 168 s driveway still should be relocated to Kallander Avenue, and driveways for Parcels 166 and 166B are made steeper. Alternative 1 does provide significant advantages over Alternative 2: one of the entrances to the driveway loop for Parcel 106 has a grade less than 10 percent. With Alternative 2, both entrances to 106 are steeper than 10 percent; therefore, Alt. 1 is recommended (raise the roadway profile of Golden View Drive near Bluebell Drive by approximately 1.5 feet. Additional coordination with adjacent property owners (Parcels 106, 166, 166B, 167, and 168) is planned and based on their input, the recommended alternative may be adjusted during the design phase. May 2013 53
C. Local Side Street Alignments and Profiles 1. Golden View Drive, south of Romania Drive Golden View Drive south of Romania Drive is an existing local road that was not constructed on the ROW centerline. This section of Golden View Drive dead-ends at Bulgaria Drive (approximately 550 feet south of Romania Drive) and then Bulgaria Drive itself dead-ends. Golden View Drive south of Romania Drive serves approximately five developed properties, located along Golden View and Bulgaria Drives. The existing grade at this location is 13.2 percent with little to no vertical curve through the intersection with Romania Drive and very steep adjacent terrain. The proposed roadway grade for Golden View Drive south of Romania Drive is 10.0 percent with a vertical curve located Golden View Drive at Romania Drive, looking south through the intersection with Romania Drive. The proposed improvements are also centered in the ROW to better accommodate the steep uphill grades to the east, including Romania Drive and two private driveways. This proposed profile is the best balance between reducing the steep roadway grade, providing an adequate vertical curve, and accommodating associated impacts to Romania Drive s grade but the grade through the intersection with Romania Drive is greater than 5 percent and thus a variance would be required per DCM requirements. The exact grade of Golden View Drive where the centerline of Golden View Drive intersects the centerline of Romania Drive is 6.74 percent (see FIGURE 11). May 2013 54
Figure 11 Proposed Grades along Golden View thru intersection with Romania May 2013 55
Sweeping the intersection of Romania Drive with Golden View Drive to accommodate the heaviest traffic movement was also investigated (see FIGURE 12). Golden View Drive would turn east onto Romania Drive as the primary movement and the section of Golden View Drive south of Romania Drive would become the stopped controlled movement. Although this configuration could potentially function efficiently now, it does not accommodate the future planned connection to Potter Valley Road. This future connection would intersect Golden View Drive at the current intersection with Romania Drive and a sweep movement from Golden View Drive onto Romania Drive east would not function efficiently with a 4-way intersection. In addition, Golden View Drive south of Romania Drive would intersect the sharp horizontal sweep at a 75 angle. This is the minimum allowed intersecting angle per the DCM. Golden View Drive south of Romania Drive would also contain a sharp crest vertical curve immediately after the intersection, which is located on a horizontal curve with a sag vertical curve profile. This is not an ideal intersection geometry. The Green Book does not recommend a sharp horizontal curve (the sweep) following a crest vertical curve (Golden View Drive south of Romania Drive). The numerous horizontal and vertical curves at this intersection could reduce stopping sight distances and clear triangle sight distance. May 2013 56
Figure 12 Sweep from Golden View Drive to Romania Drive Because of the future connection with Potter Valley Road, the steep roadway grades, and the numerous horizontal and vertical curves at the sweep intersection, it is not recommended to sweep Golden View Drive to Romania Drive east. May 2013 57
2. Bluebell Drive Kinney Engineering, LLC was contracted through a separate project to address the steep grades on Bluebell Drive. Through collaboration between Kinney Engineering and CRW Engineering, Bluebell Drive is being analyzed under a separate Design Study Memorandum, submitted by Kinney Engineering (see APPENDIX H). 3. Ransom Ridge Road The existing grade on Ransom Ridge Road is 13.1 percent with no landing and steep adjacent terrain. Approximately 400 feet west, down Ransom Ridge Road, the roadway dips in a very short, sag vertical curve before climbing in grade again. The proposed roadway grade for Ransom Ridge Road is 15.3 percent with a 25.5-foot landing at 4 percent maximum grade (see APPENDIX B). Variances would be required for the roadway grade as well as the steep grade in close proximity to the intersection. (The grade steepens to greater than 10 percent approximately 110 feet from the intersection centerline.) A profile was designed that would require no design Ransom Ridge Road, variances. The large sag looking east towards Golden View Drive vertical curve required to properly design the roadway extends the improvements along Ransom Ridge Road an additional 385 feet west, which is beyond the intersection with Stone Ridge Road. The roadway elevation at the intersection with Stone Ridge Road is 3.7 feet higher than the existing ground. The existing grade on Stone Ridge Road is approximately 11 percent (downhill away from Ransom Ridge Road). The designed improvements along Stone Ridge Road were extended for 400 feet but a proposed grade of 10 percent did not catch the existing ground. May 2013 58
Following is a summary table of impacts associated with the proposed design versus a design not requiring variances. Ransom Ridge Road impacts summary Impact Existing Conditions Proposed Design No Variances Requested (for Roadway) Driveways impacted - 1 4 Parcel 156A driveway 9.7% N/A 9.7% Parcel 156B driveway -8.8% N/A -15.0% Parcel 154B driveway 4.3% N/A -6.3% Parcel 154A driveway -2.1% -5.4% -11.9% Additional roadways impacted - 0 1 (Stone Ridge Road) A proposed roadway grade of 15.3 percent is recommended. This proposed profile is the best balance between a steep roadway grade, avoiding impacts to the short sag vertical curve, providing a landing at the intersection with Golden View Drive, avoiding impacts to Stone Ridge Road, and minimizing impacts to adjacent properties and driveways. 4. Horizontal Curves Three of the local side streets have existing horizontal curves within the proposed improvements that do not meet the DCM standards of 150-foot minimum radius: Kallander Avenue, Ransom Ridge Road, and Prominence Pointe Drive (see the table below). It is recommended these roadway horizontal radii be allowed to remain per their existing conditions to minimize impacts to adjacent properties. Horizontal roadway radius Roadway Name Kallander Avenue Ransom Ridge Road at Golden View Drive Ransom Ridge Road at Stone Ridge Road Prominence Pointe Drive Existing Horizontal Radius 120 ft 110.5 ft 145 ft 100 ft The recommendation to leave the existing horizontal curves on Kallander Avenue, Ransom Ridge Road, and Prominence Pointe Drive is supported by AASHTO s May 2013 59
Guidelines for Geometric Design of Very Low-Volume Local Roads (<400 ADT) which states: For curves on very low-volume local roads with low speeds (45 mph or less), reconstruction without changing the existing curve geometry and cross section is acceptable if the design speed of the curve is within 20 mph of the operating speed, and if there is no clear evidence of a sitespecific problem associated with the curve. (Chapter 4, pg. 30) The 2033 fully developed projected ADT is 1,407 vehicles for Prominence Pointe. There is no projected ADT for Kallander Avenue or Ransom Ridge Road. There is no history of a curve-related crash problem at any of these locations. D. Roadway Cross Section The recommended typical cross section for Golden View Drive includes two 11-foot lanes with 3.5-foot shoulders, barrier curb and gutter, an 8-foot pathway on the west side, and a drainage ditch on the east side. The shoulders should be striped with Bike Lane symbols. (See the section below for an analysis of the recommended pedestrian facilities and SECTION VII. DRAINAGE ANALYSIS for recommended drainage facilities.) The total width from back of curb to back of curb is 33 feet (see FIGURE 13). Type 1, barrier curb and gutter provides a greater safety measure for pedestrians on the pathway, discourages parking on the shoulder or pathway, and also discourages full frontage width vehicular access of adjacent properties by defining specific driveway curb cuts. AASHTO s Roadside Design Guide (RDG), which addresses clear zone requirements, is most applicable on rural, high-speed freeways. Golden View Drive is being designed to urban standards, with barrier curb & gutter, pedestrian facilities, bicycle lanes, and illumination. A full-width clear zone in accordance with the RDG is not appropriate on this urban-designed roadway. Additionally, ADOT would consider Golden View Drive upgrades as a 3R project. Since there are no run-off-the-road crash problems along Golden View Drive, ADOT s Pre-Construction Manual would not require the roadway cross section to be changed from existing conditions. The total available clear width on the downhill (west) side is 15 to 19 feet from the edge of the travelled way. On the uphill (east) side, the total available clear width is 7 feet from the edge of the travelled way. May 2013 60
Figure 13 Proposed Typical Cross Section May 2013 61
E. Pedestrian Facilities There are currently no pedestrian facilities along Golden View Drive. Pedestrians utilize the roadway and shoulders for recreational and commuting activities. Because the ASD has designated Golden View Drive as a hazardous walking route due to the lack of pedestrian/bicycle facilities, school children are not allowed to walk to Pedestrians along Golden View Drive Goldenview Middle School along Golden View Drive. Preliminary coordination with the Anchorage School District indicated that in the future, portions of Golden View Drive may be considered for inclusion in the safe walking routes to Goldenview Middle School with appropriate pedestrian facilities and lighting. Further coordination with the Anchorage School District will be conducted during the design phase to determine safe walking routes along Golden View Drive. Due to the steep grades bordering the roadway corridor, various alternatives for pedestrian facilities were investigated to minimize impacts to adjacent properties and drainage ways. All of the alternatives below include pedestrian facilities that are separated from the roadway by barrier curb and gutter to further delineate the pedestrian route from the vehicular route. 1. Alternative 1: Pathway west side only Alternative 1 consists of one, 8-foot wide paved pathway on the west side of the roadway only. The pathway would run the entire project corridor (begin at Romania Drive and terminate at Rabbit Creek Road). The pathway would be separated from the back of curb where feasible but would be attached to the back of curb as needed to minimize impacts to adjacent properties and wetlands. May 2013 62
2. Alternative 2: Pathway on west side, sidewalk on east side Alternative 2 consists of an 8-foot wide paved pathway on the west side of the roadway and a 5-foot wide sidewalk on the east side. Both the pathway and the sidewalk would run the entire project corridor. The pathway would be separated from the back of curb where feasible but would be attached to the back of curb as needed to minimize impacts to adjacent properties and wetlands. The sidewalk would be attached to the back of curb. 3. Alternative 3: Pathway west side, sidewalk on east side partial length Alternative 3 consists of an 8-foot wide paved pathway on the west side of the roadway and a 5-foot wide sidewalk on the east side. The pathway would run the entire project corridor but the sidewalk would begin at Prominence Pointe Drive and terminate at Rabbit Creek Road. Similar to Alternative 2, the pathway would be separated from the back of curb where feasible but would be attached to the back of curb as needed to minimize impacts to adjacent properties and wetlands. The sidewalk would be attached to the back of curb. 4. Alternative 4: Pathway west side, sidewalk on east side partial length Alternative 4 is similar to Alternative 3 except the sidewalk would begin at Prominence Pointe Drive and terminate at Bridgeview Drive. A crosswalk would be installed at Bridgeview Drive. 5. Alternative 5: Pathway east side only Alternative 5 consists of one, 8-foot wide paved pathway on the east side of the roadway only. The pathway would run the entire project corridor (begin at Romania Drive and terminate at Rabbit Creek Road). The pathway would be separated from the back of curb by a 4-foot buffer. May 2013 63
The existing topography immediately uphill of the project corridor (east side) is often steep with high ground water. Permitting regulations require construction of a ditch to maintain open channel flow of the multiple drainage ways and creek tributaries. Installing curb and gutter, a pedestrian facility, and a ditch on the east side would result in significant impacts to adjacent properties, drainage ways, creek tributaries, and utilities. Golden View Drive looking south The neighborhood has expressed a desire to retain the rural feel of the area with minimal clearing on adjacent properties. The extensive grading impacts from installing a sidewalk and a drainage way on the east side would require approximately 5,000 additional square feet of retaining walls. In addition, utility relocation costs would be approximately: $2.58 million (Alternative 1) $3.87 million (Alternative 2) $2.83 million (Alternative 3) $2.61 million (Alternative 4) $4.37 million (Alternative 5) This equates to an additional utility relocation cost ranging from approximately $23 thousand (Alternative 4) to $1.7 million (Alternative 5) compared to Alternative 1. A preliminary estimate indicates that adding a 5-foot sidewalk on the east side of the roadway would cost an additional $7 million. This includes sidewalk materials and construction, retaining walls, additional impacts to connecting side streets, additional May 2013 64
impacts to adjacent driveways, additional impacts to drainage ways, and additional utility relocation costs (including a fiber optic line and a pressurized 12-inch gas main on the east side of the ROW). With no pedestrian facility on the east side, the side street grades can be a maximum of 4 percent within 30 feet from the edge of Golden View Drive. If a pedestrian facility were installed on the east side, the roadway grade across the pedestrian access route can only be a maximum of 2 percent. Therefore, it is recommended that a pedestrian facility only be installed on the west side (Alternative 1) to minimize impacts to adjacent properties, wetlands, creeks, drainage ways, and utilities. F. Side Street Intersections/Access Control Kinney Engineering, LLC performed an analysis of side street intersection and access control to determine if auxiliary turn lanes were warranted at various cross streets. Capacity analyses at the major cross-street intersections indicate that auxiliary turn lanes are not required to achieve adequate LOS. Using AASHTO s guidelines for determining turn lanes at intersections, left turn lanes are recommended at E. 156 th Avenue, Goldenview Middle School driveway, and Prominence Pointe Drive. Due to impacts to adjacent streams, wetlands, terrain, and private property associated with adding additional width to the roadway, construction of auxiliary turn lanes is not practical. Adequate LOS can be achieved without left turn lanes; therefore, left turn lanes are not recommended at E. 156 th Avenue, Goldenview Middle School driveway, or Prominence Pointe Drive. Additionally, the current configuration of Goldenview Middle School s driveway allows for cooperative or courteous gaps to allow for vehicles to exit or enter the school during peak hours. If a turn lane were added, the cooperative gaps would most likely not occur because two lanes of traffic would be required to cooperate simultaneously to allow for a gap. G. Rabbit Creek Road/Golden View Drive Intersection Various alternatives were analyzed for improving the intersection of Rabbit Creek Road and Golden View Drive. In November 2011, an Intersection Analysis Report was submitted to ADOT for review (see APPENDIX G for the full Intersection Analysis Report). A meeting was held with ADOT in December 2011 to discuss the alternatives and proposed improvements at this intersection. May 2013 65
ADOT expects to study and analyze the hillside intersections, including the intersection of Rabbit Creek Road and Golden View Drive. Although this intersection has an aboveaverage crash rate, it does not currently have an above-average crash severity rate. Because of this statistic, combined with the planned Hillside Intersection Study, improvements to the intersection of Rabbit Creek Road/Golden View Drive are currently onhold and are not anticipated to be included with the Golden View Drive project. H. Structural Section The MOA s Design Criteria Manual states that road sections should be designed to minimize the following: frost penetration into frost susceptible subgrade soil, movement of fine grained soil into the structural section, and differential frost heaving. These objectives are typically accomplished by providing either a sufficient thickness of non-frost susceptible (NFS) fill or a lesser amount of fill combined with insulation. Based on the existing F2-F3 soil along most of the alignment, it is estimated that 8.5 to 10.4 feet of NFS would be required to limit subgrade frost penetration to meet the DCM guidelines. If insulation is used to provide frost protection, the overall thickness of NFS fill may be reduced to approximately 4 feet. The insulation should extend beyond the back of curb a minimum of 2 feet to limit lateral frost penetration. Additionally, detailed consideration needs to be given to the transition between insulated sections and non-insulated sections, such as at the beginning and end of the insulated section, as well as at the side streets and driveways. The insulation needs to be transitioned to minimize differential heaving that can occur at the division between insulated and non-insulated sections. Appropriate transitions can include extending the insulation beyond the roadway improvements, reducing the insulation thickness, or angling the insulation downward. Use of a frost tolerant section, an alternative to the insulated section, may be warranted where subgrade soil has low to moderate frost susceptibility or where groundwater is relatively deep and subgrade soil is not saturated most of the year. A frost tolerant section could be considered at the beginning of the project, from approximate station 508+00 to about station 520+00. Soil borings in this area encountered shallow weathered rock, between 2.5 feet to 12 feet below ground surface. A frost tolerant section may also be considered at the north end of the project, between approximate stations 590+00 to 599+50. General appearance of the pavement surface suggests that roadway performance in this segment is better than the remainder of the alignment. A frost tolerant section in these two segments would consist of approximately 2.25 feet of NFS fill material. May 2013 66
For both an insulated and frost tolerant section, a non-woven geotextile is included along the base of the structural section to separate the native silty subgrade materials from the imported subbase fill. When peat is exposed in the base of the excavation, it is recommended that the peat be excavated out and replaced with imported fill. I. Retaining Walls Due to the steep adjacent terrain along the project corridor, retaining walls will be required to reduce the impacts from roadway grading and slopes. Retaining walls should be installed as needed to minimize impacts to utilities, the environment, and adjacent properties. 1. Retaining Wall Types Below is a description of the four basic types of retaining walls along with their characteristics. Gravity: Gravity retaining walls rely on the mass of the wall structure for stability. The wall mass must be sufficient to counteract sliding and overturning forces from the retained soil. These systems can use stone, concrete or other heavy material as well as mechanically stabilized earth (MSE) for stability. These are the most common type of reretaining walls and include gabions, bin walls, and modular block concrete construction. In most cases the slope behind the wall needs to be temporarily removed during construction. For mechanically stabilized earth walls, the reinforcing often extends horizontally into the embankment about as far as the exposed wall face is tall. Example rock-gabion retaining wall Example modular block retaining wall May 2013 67
Piling: Piling retaining walls have structures that extend significantly below grade to provide support to counteract horizontal forces from the retained soils. Typically two thirds of the structure height is embedded below grade. The structures are usually steel sheet piles or H beams. Piles are driven into the soil while H beams can either be driven in or set into drilled holes. Quite often, the structural face of a piling wall is covered with a facade of concrete blocks or panels. These are some of the most expensive types of retaining walls but they do allow construction with very little removal of soil behind the wall. Cantilever: Cantilever retaining walls have a large effective mass due to the soil placed over a horizontal section of the wall. These walls are typically constructed of cast-inplace, reinforced concrete. The horizontal (cantilevered) leg of the structure can either extend back into the retained soil or out away from the slope. The slope behind the wall typically needs to be temporarily removed during construction. Cantilever walls are relatively expensive due to the work required to build concrete forms, install reinforcing, pour concrete, and provide joints between pours. The concrete needs ample time to cure before the soil can be replaced behind the wall. Anchored: Anchored (or tieback) retaining walls use cables driven horizontally into the soil to counteract opposing horizontal forces from the retained soils. The anchors, which typically pull horizontal plates or sheets against the soil, can be soil nails, tieback cables, or screw anchors. The soil behind the wall does not need to be removed during construction. The anchors may need to extend into the embankment quite a ways, which can impact buried utilities or future development. Combination: Many retaining walls use a combination of the above types. For example, many piling walls use anchors to reduce embedment depth and structure strength. 2. Considerations The decision to construct a retaining wall can be subjective and must balance the cost of installing a retaining wall with the overall impacts to utilities, wetlands, the environment, or adjacent properties. Impacts to wetlands often demand construction of retaining walls due to permitting requirements to avoid or minimize wetlands impacts if possible. Exact locations of retaining walls will require further refinement during the design phase. Below are important considerations that affect the decision to provide a retaining wall and which type of wall should be constructed. May 2013 68
Basic types of retaining walls Embankment Impacts: Gravity and cantilever retaining walls typically require some of the soil behind the wall to be temporarily removed during construction. In some cases the slope can be cut to stand near vertical for short periods of time to reduce impacts but OSHA embankment guidelines and worker safety must be accounted for. Piling walls can minimize impacts to adjacent properties and structures. Foundation Soils: Gravity and cantilever retaining walls require a solid foundation to resist the forces of the wall and soil. Where foundation soils are weak, a piling or anchor wall should be considered or the weak soil replaced. The bedrock encountered near the south end of the Golden View Drive project provides an excellent foundation but makes driving sheet piles very difficult (see APPENDIX E for the geotechnical report). Groundwater/Drainage: Groundwater needs to be removed from behind the retaining wall to reduce hydrostatic forces. Many types of wall are inherently porous while other May 2013 69
types, like reinforced concrete, require weep holes to be integrated into the design to relieve pressure from water behind the wall. In areas where substantial groundwater and glaciation is expected, a subdrain should be considered to direct the runoff to drainage ditches or a piped storm drain collection system. Utilities: Some types of retaining walls impact a considerable amount of soil behind the face of the wall. For example, modular block walls and MSE walls rely on reinforcing geotextile fabric embedded into the soil as part of the structure. The fabric behind the wall can impact existing utilities or limit future placement of utilities. Anchor wall cables also extend into surrounding soils and affect utilities. Aesthetics: Retailing walls are often very noticeable along a roadway corridor and they should be selected to compliment the landscaping design and blend in with the surrounding neighborhood. Sometimes retaining walls are chosen to match existing walls on adjacent properties. Many of the existing retaining walls along Golden View Drive are large irregular boulders. Although many PM&E roadway project use concrete modular block retaining walls, gabion walls may be more appropriate for this project area where residents have expressed a desire to retain the rural feel. Gabion walls have also been used in other Anchorage hillside areas including along Birch Road and for South Anchorage High School. Safety Fence or Handrail: When the vertical face of the retaining wall is more than 2.5 feet tall, a fence, handrail, or guardrail should be provided for safety. Moose should be discouraged from walking over the wall. Where space is limited, a fence or handrail can be placed near the face of a reinforced concrete wall. Most other types of wall require the fence to be set back in the soil behind the wall. Construction Schedule: In some cases, the amount of time required to construct a retaining wall is very important since it can affect impacts to adjacent property owners or the environment. Reinforced concrete headwalls take a considerable amount of time to May 2013 70
construct. They are typically not a good option for stream culvert headwalls that need to be completed quickly to reduce environmental impacts. Maintenance: Retaining walls and associated fences or handrails should be designed to require little if any maintenance. Concrete surfaces can be provided with coatings to facilitate removal of spray paint vandalism. Construction of gabion-type retaining wall Cost: The estimated installed cost for retaining walls varies considerably from $45 to more than $200 per square foot of the exposed vertical face. Some of the biggest factors include soil conditions, wall height, tiebacks, construction access, type of fence and the amount of soil to be removed behind the wall for construction. On the following page is a summary of orderof-magnitude cost for various types of retaining walls for comparison purposes. These costs include a chain link fence above the wall. Construction of modular block retaining wall Example modular block retaining wall with railing May 2013 71
Retaining Wall Type Modular block (Keystone), without tiebacks Modular block (Keystone), geogrid tiebacks Summary of Unit Costs Cost per Square foot of wall face, installed $45 Excavation full excavation behind blocks, limited to 4' height $60 full excavation behind geogrid Mechanically Stabilized Earth (MSE) $75 with concrete face, full excavation behind wall and tieback Gabion Basket $75 full excavation behind wall Reinforced concrete, cast-in-place Soldier pile, without tiebacks $120 $130 full excavation behind base of structure with block facade, minimal excavation behind wall Soldier pile, with tiebacks $190 Sheet pile, without tiebacks $180 Sheet pile, with tiebacks $210 with block facade, minimal excavation behind wall with block facade, no excavation behind wall with block facade, no excavation behind wall 3. Estimated Project Cost The conceptual drawings located in APPENDIX B indicate where retaining walls should be considered to limit impacts to utilities, the environment or adjacent property. The potential areas for retaining walls for the preferred alternative (Alternative 1) are summarized below in TABLE 6. Note: this summary does not include stream culvert headwalls. May 2013 72
Street Table 6 Summary of Retaining Walls (preferred alternative) Approx. Start Station Ave Height (ft) Length (ft) Area (sf) Utility Purpose Offset Environment Property Golden View 528+75 Left 4.9 181 887 X Golden View 531+27 Right 3.5 108 378 X X Golden View 535+34 Right 5.2 28 146 X Golden View 541+27 Right 6.4 285 1,824 X X Golden View 543+88 Left 2.5 65 163 X Golden View 544+69 Left 2.0 107 214 X Golden View 546+45 Left 3.0 296 888 X Golden View 549+72 Right 4.0 667 2,668 X X Golden View 568+81 Right 3.4 116 394 X Golden View 570+69 Left 3.5 572 2,002 X X Golden View 577+45 Left 2.5 542 1,355 X Golden View 584+65 Left 4.5 530 2,385 X Romania 200+78 Left 4.1 38 156 X A modular block or gabion basket type retaining wall can be used in nearly all of the areas identified above. Assuming a unit cost from $60 to $75 for modular block and gabion basket wall types respectively, this represents an approximate cost of $880 thousand to $1.01 million for the recommended Alternative 1. J. Traffic Calming Based on speed studies and comments from local residents, speeding is a concern. Various methods for traffic calming were investigated, including: Vertical traffic calming measures (ex. speed hump) Horizontal traffic calming measures (ex. neckdowns) Full or partial closures Center islands narrowing Colored crosswalks Roadway striping Due to the vertical curves and steep grades along Golden View Drive, locations for vertical or horizontal traffic calming measures are limited. Speed humps and neckdowns are most May 2013 73
appropriate on flat, straight roadways with less than 30 MPH posted speeds. Speed humps are also discouraged on collector roadways and are not recommended on primary emergency routes or bus routes. Golden View Drive is the primary route into and out of many of the adjacent neighborhoods and speed humps significantly reduce the response time of emergency vehicles. Traffic calming features that significantly reduce traffic volumes, like diverters and partial or full-closures are not appropriate on collector roadways. These measures tend to divert traffic onto adjacent residential streets and reduce the efficiency of the transportation system. Roadway striping will be installed along the entire project corridor, including shoulder stripes, which will effectively reduce the visual appearance of the travel lane widths. The visual appearance of narrower lanes, as compared to feeling comfortable utilizing the entire roadway surface, reduces traffic speed. Shoulder stripes can also serve a dual purpose by designating the shoulder as a bike lane and reducing the visual dimensions of the travel lane. Existing short vertical curves also serve as traffic calming measures. K. Lighting The DCM s lighting requirements are based on the IESNA RP-8-00 American National Standard Practice for Roadway Lighting. Golden View Drive is designated as a collector for lighting standards in the IESNA (Section 2.1). The IESNA does not make recommendations or provide guidelines for partial lighting of intersections only (Section 1.1). It only provides recommendations for designing continuous lighting systems for roadways. Transition lighting is recommended in the IESNA to provide a driver with gradual reduction in lighting levels when leaving a lighting system. As an example, if only the intersections along Golden View Drive were illuminated, transition lighting should be installed along the roadway to gradually adjust the driver s eye to the intersection lighting levels. The transition lighting would most likely extend to the adjacent intersections, resulting in continuous roadway lighting. Several studies have also shown that the primary benefit of lighting intersections along major streets is a reduction in night pedestrian, bicycle, and fixed object crashes (Section 3.6.2) and proper intersection lighting is a critical design component. Intersections should be illuminated to increase safety. May 2013 74
To reduce the length of the vertical curves along the roadway profile, lighting is required for visibility and sight distance. If lighting were not installed, the vertical curves would be significantly longer and result in a wider roadway footprint, thus the impacts to adjacent properties, wetlands, drainage ways, and utilities would also be significantly larger. The new lighting system will need to achieve the light levels and uniformity ratios required for a collector roadway, including the pathways and intersections. The system will include rounded steel poles that provide a 30 to 40-foot luminaire mounting height and include tapered mast arms that locate the luminaires in the positions determined by the lighting analysis. Per Chapter 5 of the DCM, along roadways with posted speeds of 40 MPH or greater, poles shall have Example of the white light from LEDs breakaway bases. In urban areas were speeds are between 30 and 40 MPH, luminaire pole bases may be breakaway or non-breakaway. In selecting breakaway versus non-breakaway bases, consideration should be given to balancing the hazards to pedestrians and vehicles from falling (breakaway) poles versus the impact on a vehicle and its occupants with a non-breakaway base. The system also will include light emitting diode (LED) luminaires that provide a full cutoff light distribution. The poles are to be located on property corners, where feasible, to reduce the light trespass into adjacent homes. Light levels and uniformity ratios on collector road, pathways, and at the intersections are summarized below: Road: The DCM recommends a minimum maintained average of 0.6 foot-candles with an average-to-minimum uniformity ratio no greater than 4:1 and a veiling luminance ratio no greater than 0.4. Pedestrian Facilities: Pedestrian activity along Golden View Drive meets the low criteria provided in Chapter 5 of the DCM. For adjacent pedestrian facilities within the low pedestrian volume criteria, Chapter 5 of the DCM includes three light level requirements based on land use: rural/semi-rural, low-density residential, and mediumdensity residential. In areas with single family homes (low-density residential), a minimum maintained average of 0.3 foot-candles with an average-to-minimum uniformity ratio no greater than 6:1 is required. May 2013 75
Intersections: For the purpose of lighting intersections, the DCM uses the following roadway classifications (note these do not apply to standard street classifications): o o o Major: over 3,500 ADT Collector: 1,500 to 3,500 ADT Local: 100 to 1,500 ADT For the design year, Golden View Drive north of Bluebell Drive is functionally classified as a Major road for analyzing intersection lighting. South of Bluebell Drive, Golden View Drive is a Collector road. For the design year, all side streets are classified as Local roads, except E. 156 th Avenue which is classified as a Collector road for intersection lighting. Below is a summary of intersection lighting requirements from the DCM: Illuminance for Intersections* Functional Classification Average Maintained Illuminance (low pedestrian area) Maximum Uniformity Ratio Major/Major 1.8 3.0 Major/Collector 1.5 3.0 Major/Local 1.3 3.0 Collector/Local 1.0 4.0 *From DCM Table 5-5 L. Landscaping The overall goal of the landscape design is to limit impacts to existing vegetation where feasible and provide new landscaping where space allows. The width of existing ROW is primarily 60 feet and can accommodate road, pedestrian, and drainage improvements but provides little to no additional room for new landscape improvements. The project design will strive to protect existing mature trees on private property that are adjacent to the proposed improvements. Vertical landscaping elements that are installed adjacent to the roadway can act as traffic calming measures as they provide visual cues to drivers to reduce speeds. These cues can consist of planters, lighting, or even sculptural elements. It is important that vertical elements do not impede visibility of pedestrians or vehicles and any such elements are to be installed in such a way that they are compatible with maintenance needs, such as snow removal and storage. May 2013 76
The use of neighborhood gateways has become a common way to add interest to streetscapes, provide neighborhoods with a unique identity, and provide visual clues to drivers that they are entering a neighborhood. They have been very successful in some neighborhoods and less so in others. Typically, the gateway features are most successful in neighborhoods that already possess a strong individual identity within their Native vegetation near Goldenview MS community. Prominence Pointe subdivision currently has a gateway feature at the intersection of Prominence Pointe Drive and Golden View Drive. Native topsoil may be stripped and stockpiled from areas where construction is to take place within the project alignment. Stockpiled native topsoil can be reused and takes advantage of the valuable native seed stock within it. Reuse of native topsoil is an effective way to revegetate with native plants without importing large amounts of non-native topsoil. Importing non-native topsoil can be costly and it can introduce invasive plant species to an area unnecessarily. M. Trails Trail easements have been identified at two locations along the project alignment. One easement is located at Little Rabbit Creek between parcels 133 and 133A. The other is located on parcel 172. Even though trails do not currently exist at these locations, it is intended that access to them be maintained as a part of the project so that future trail heads will not be impeded. This adheres to the Hillside District Plan s Chapter 2, Goal 6 of maintaining, supplementing and enhancing a system of parks, trails, open spaces and other active and passive recreation areas. May 2013 77
N. Cluster Mailboxes Cluster mailboxes are desirable to the MOA and the United States Postal Service as they facilitate maintenance, reduce delivery times, and provide a secure receptacle for the residents. The existing cluster mailboxes located at the south end of the project (across from Moen Cluster mailboxes on Golden View Dr., south of E. 156 th Park) and at the north end of the project (near E. 156 th Avenue) are to remain. At this time, there are no plans to replace the existing single-serve mailboxes with cluster boxes. O. Parking Golden View Drive is designated as a residential collector, which emphasizes a higher degree of mobility than access to adjacent properties. Given the large lot size of adjacent properties, with generally longer driveways and parking pads, combined with the emphasis on mobility along Golden View Drive, on-street parking is not recommended. May 2013 78
VII. Drainage Analysis A. Existing Planning Documents The planning document Pilot Watershed Drainage Plan for Little Rabbit Creek and Little Survival Creek Watersheds December 2008 (WDP) includes watershed characterization, runoff modeling, and recommendations for drainage infrastructure improvements and runoff controls. Policy recommendations are also presented to promote watershed-wide drainage management. It is a goal of this project to implement recommendations made in the Watershed Drainage Plan within the Golden View Drive ROW. B. Storm Water Model A storm water model was assembled and computed to determine size and location of drainage facilities along Golden View Drive. As part of the drainage analysis effort, the peak discharge was calculated at key locations to properly size storm drain piping, catch basins and other storm drainage appurtenances for both the existing and proposed conditions. Additionally, analysis results were compared to those of the WDP to verify agreement with conveyance structure sizes. The drainage analysis approach is consistent with industry standards and the MOA PM&E DCM and accompanying Drainage Design Guidelines. Supporting data and modeling for the drainage analysis is found in APPENDIX F. The existing and proposed storm drainage systems have been modeled with Bentley CivilStorm V8 computer modeling software. The peak stormwater discharge was determined for both conditions. The SCS Curve Number method was used to develop rain-runoff response. As published in the MOA PM&E DCM, the SCS Type I, 10-year, 24-hour duration storm distribution was modeled for peak discharge conveyance design. Additionally, peak storm water discharge for the SCS Type I, 2-year, 24-hour storm event was analyzed for storm water treatment purposes. Based on the location of the project area, orographic factors varying from 1.30 to 2.13 has been applied to adjust the 1.77-inch and 1.26-inch base storm volumes for conveyance and water treatment design, respectively. Storm event data and drainage analysis input parameters are found in APPENDIX F. The drainage basins were further refined and adjusted from GIS data obtained from MOA Information Technology Department and WMS. The computer software ArcMap by ESRI was used to view and analyze GIS data in conjunction with aerial imagery to determine impervious areas, slope and land cover. Once the basin data was compiled from ArcMap, May 2013 79
Microsoft Excel was used to compute the necessary input parameters required for both the existing and proposed CivilStorm drainage models. The storm water runoff generated from each subbasin is summarized below in TABLE 7. For modeling and analysis purposes, undeveloped areas have been considered fully developed to ensure the proposed drainage improvements are sized to convey increased future storm runoff. Table 7 Summary of storm water runoff Subcatchment Area 1-yr 24-hr 10-yr 24-hr UNIT (Acre) (cfs) (cfs/ac) (cfs) (cfs/ac) B101 23 0.3 0.02 4.7 0.21 B102 9 0.1 0.01 1.8 0.08 B103 3 0.3 0.12 1.3 0.06 B104 33 0.6 0.02 6.0 0.27 B105 5 0.5 0.09 2.2 0.10 B106 39 0.8 0.02 8.5 0.38 B107 3 0.4 0.11 1.3 0.06 B108 36 1.3 0.04 9.9 0.44 B109 1 0.4 0.69 0.9 0.04 B110 51 1.3 0.02 10.0 0.44 B111 55 8.2 0.15 26.3 1.16 B112 4 1.2 0.31 3.4 0.15 B114 22 12.6 0.56 27.0 1.19 B115 20 1.7 0.08 8.5 0.38 B116 8 2.1 0.25 6.2 0.28 B117 94 14.6 0.16 44.5 1.97 B118 5 1.0 0.21 3.0 0.13 B119 58 2.6 0.05 16.9 0.75 B120 123 2.5 0.02 22.9 1.01 B400 229 33.1 0.14 114.6 5.07 B401 88 3.8 0.04 31.3 1.38 B402 60 3.7 0.06 21.2 0.94 B403 29 2.3 0.08 11.4 0.51 B404 62 2.4 0.04 18.5 0.82 May 2013 80
C. Proposed Drainage System The proposed drainage system is made up of five separate systems, each with their own outfall. Site topography and existing stream and drainages necessitates using separate systems. Common to each system is use of typical CPEP piping, catch basins and catch basin manholes for storm drain mains. Stream crossings larger than approximately 4 feet in diameter may be concrete, aluminum, or steel structures as determined during detailed design. Existing roadside ditches and drainage ways on the east or uphill side of Golden View Drive will be maintained or reconstructed. Side street ditches will be installed and/or improved where streets are being modified. At cases where ditch grades are relatively steep, permanent ditch armoring will be constructed for erosion protection. The five systems are described below, start at the southern end of the project. System 1 System 1 extends generally from station 508+00 near Romania Drive to station 514+60. The flow direction is from north to south. This system collects primarily roadway runoff and consists of standard catch basins and catch basin manholes. The existing culvert crossing at the intersection of Golden View Drive and Romania Drive which carries the Potter Branch (refer to Stream Crossings table) drainage will be replaced and incorporated into this system. A treatment facility will be incorporated into the system prior to discharge. Based on limited availability of land and challenging topography, the treatment facility will likely be a vault-type treatment unit. Conceptual graphic of a culvert crossing May 2013 81
System 2 System 2 extends from station 518+00 to station 522+10. The flow direction is from south to north. This system collects roadway runoff. The existing culvert crossing at station 522+10 which carries the South Fork Little Survival Creek drainage will be replaced. A treatment facility will be incorporated into the system prior to discharge. Based on limited availability of land and challenging topography, the treatment facility will likely be a vaulttype treatment unit. System 3 System 3 extends from station 526+40 to station 531+50 just north of Bluebell Drive. The flow direction is from the south and north to the stream crossing at station 529+30. The existing culvert crossing at station 529+30 which carries the South Branch Little Survival Creek drainage will be replaced. Runoff from the lower portion of Bluebell Drive will be collected by this system. This includes both runoff from the roadway and also roadside ditches. A treatment facility will be incorporated into the system prior to discharge. Based on limited availability of land and challenging topography, the treatment facility will likely be a vaulttype treatment unit. A diversion structure or typical manhole will be used to outfall treated roadway runoff into the natural drainage. Conceptual graphic of a roadside ditch System 4 System 4 extends from station 533+00 to station 534+70. The flow direction is from south to north. This system collects roadway runoff. The existing culvert crossing at station 535+70 which carries Little Survival Creek will be replaced. A treatment facility will be incorporated into the system prior to discharge. There may be an opportunity to install a small natural treatment system East of Goldenview Drive between the outfall at 534+75 and the creek culvert at station 535+70. May 2013 82