(BRIDGE NO. 36C-0223)

Transcription

1 City of Palo Alto Newell Road Bridge Replacement (BRIDGE NO. 36C-0223) TYPE SELECTION REPORT DRAFT November 2012

2 City of Palo Alto Newell Road Bridge Replacement (BRIDGE NO. 36C-0223) TYPE SELECTION REPORT DRAFT November 2012 Submitted to: Joe Teresi City of Palo Alto Department of Public Works 250 Hamilton Avenue Palo Alto, CA Prepared by: NV5, Inc Gateway Place, Suite 156 San Jose, CA 95110

3 TABLE OF CONTENTS EXECUTIVE SUMMARY... ERROR! BOOKMARK NOT DEFINED. PROJECT PURPOSE AND NEED... ERROR! BOOKMARK NOT DEFINED. PROJECT LOCATION...1 PROJECT DESCRIPTION...3 PROJECT ALTERNATIVES...4 ROADWAY ALIGNMENT ALTERNATIVES...5 BRIDGE ALTERNATIVES...7 BRIDGE AESTHETICS...10 TECHNICAL DESIGN DATA...10 PROJECT CONSTRUCTION METHODOLOGY...15 ENVIIRONMENTAL PERMITTING...17 PROJECT / BRIDGE TYPE RECOMMENDATION...17 APPENDICES APPENDIX A Approved E-76 Form / PES APPENDIX B Roadway Alignment Alternatives APPENDIX C - Bridge General Plan and Estimate APPENDIX D Conceptual Bridge Aesthetic Renderings APPENDIX E Geotechnical Memorandum APPENDIX F Hydraulic Technical Memorandum APPENDIX G Traffic Evaluation Report Newell Road Bridge-Type Selection i SJB036700

4 EXECUTIVE SUMMARY The City of Palo Alto intends to replace the existing Newell Road Bridge at San Francisquito Creek. Newell Road is classified as an urban collector street and the bridge links the City of Palo Alto and City of East Palo Alto as well as the Counties of Santa Clara (CPA Side) and San Mateo (EPA side). The purpose of this project is to replace the existing functionally obsolete and hydraulically deficient bridge on Newell Road, crossing San Francisquito Creek, with a new vehicular bridge that: 1) Provides City of Palo Alto and City of East Palo Alto standard lane, shoulder, and sidewalk widths (11 feet, 5 feet, and 5 feet) as prescribed by each of the city s street standards 2) Provides safe vehicle, bicycle, and pedestrian access across San Francisquito Creek, and 3) Accommodates the 100-year storm (Q-100) flow of San Francisquito Creek Three project alternatives have been evaluated for the replacement of the existing Newell Road Bridge: 1) Pedestrian/ Bicycle Bridge 2) Vehicular Bridge on Exiting Newell Road Alignment 3) Vehicular Bridge on Realigned Newell Road Alignment The pedestrian / bicycle bridge alternative does not meet the stated purpose and need of the project, but was analyzed never-the-less in order to address comments received at the initial public outreach meeting for the Newell Road Bridge on June 27, A traffic study was conducted to determine the impacts to the local traffic patterns if the replacement bridge was constructed exclusively for pedestrian and bicycle traffic. The study concluded that closing Newell Road to vehicular traffic across San Francisquito Creek would divert the 3020 vehicles per day currently crossing the existing bridge to local non-collector residential streets in the City of Palo Alto which would create a negative impact to the local community and push traffic to intersections along University Avenue not currently designed for the predicted increase in traffic volumes. As a result of the traffic study conclusions and the fact that the pedestrian/bicycle bridge does not meet the stated purpose and need of the project, the pedestrian/bicycle bridge option has been dropped as a viable alternative for the replacement of the existing Newell Road Bridge. Alternatives 2 and 3 were further evaluated to determine the preferred alternative for the replacement of the exiting Newell Road Bridge. This evaluation concluded that the preferred project alternative is Alternative 3, Vehicular Bridge on Realigned Newell Road Alignment, containing the following features: Bridge / Roadway Vertical Profile: The recommended bridge and roadway profile sets the replacement bridge soffit such that Q-100 flow of San Francisquito Creek can pass beneath the bridge unobstructed, as preferred by the Santa Clara Valley Water District (SCVWD). In order to limit the increase in the bridge s vertical profile and to reduce Newell Road Bridge-Type Selection 1 SJB036700

5 impacts to the local community, creek bank improvements extending approximately 800 feet downstream of the Newell Road Bridge, as proposed by the SCVWD to provide 100- year flood protection in this stretch of the creek, will be constructed as part of this bridge replacement project. Downstream San Francisquito Creek Bank Improvements: Creek bank improvements extending approximately 800 feet downstream of the existing Newell Road Bridge will be incorporated into the scope of the project. These improvements allow the proposed vertical road alignment to be lowered by approximately 0.8 feet from the profile that would be needed to pass the Q-100 flow without the improvements Roadway Horizontal Alignment: Design Alternative 3, the realigned road option, is the recommended alternative because the realigned road: o Results in a safer and more traditional 4-way intersection. o Improves sight distances for vehicles at the Newell/Woodland intersection o Results in a more direct route along Newell Road for pedestrians and bicyclists o Results in lower retaining wall heights compared to Alternative 2, and thus has less visual impact to the local residents Bridge Type: A cast-in-place post-tensioned concrete slab superstructure is the recommended bridge type for the Newell Road Bridge replacement structure. This structure type is the least expensive, provides the lowest deck elevation possible, and accommodates the construction of the proposed pedestrian overlooks Bridge Aesthetics: The recommended bridge architectural features include: o Type 80SW barrier to provide drivers with an open feel to the bridge, with impact-resistant glazing filling the 5-foot long by 11-inch high openings to provide required the 4-foot FEMA freeboard above the Q-100 water surface elevation. o Fluted lighting standards traditionally used in elsewhere in Palo Alto. o Curved 16-foot wide overlooks at the mid-span of the bridge that extend 7 feet out beyond the edge of deck o Further consideration of additional aesthetic features for the bridge will be undertaken after the preferred bridge type is selected and an artist is retained by the City of Palo Alto Public Art Commission. Project Construction Methodology: The recommended construction methodology for the replacement of the existing Newell Road Bridge and associate roadway approach work is to close Newell Road to public traffic, provide a detour using local streets, demolish the existing bridge, and build the bridge as an entirely new structure. Newell Road Bridge-Type Selection 2 SJB036700

6 PROJECT LOCATION The Newell Road Bridge Replacement Project is located on Newell Road at the crossing of San Francisquito Creek. This crossing is the boundary between Palo Alto and East Palo Alto as well as the boundary between Santa Clara County and San Mateo County. PROJECT VICINITY MAP No Scale Newell Road is classified as an urban collector. The current bridge provides access between Palo Alto and East Palo Alto and carries an Average Daily Traffic (ADT) of approximately 3000 vehicles per day. PROJECT DESCRIPTION The City of Palo Alto intends to replace the existing Newell Road Bridge at San Francisquito Creek (SFC). Newell Road is classified as an urban collector street and the bridge links the City of Palo Alto (CPA) and City of East Palo Alto (EPA) as well as the Counties of Santa Clara (CPA Side) and San Mateo (EPA side). The bridge crosses over SFC and intersects with Woodland Avenue in EPA. The existing reinforced concrete bridge (sufficiency rating of 35.4) is considered functionally obsolete and has abutments located within the SFC creek bed which cause a flow constriction within the channel. SFC is in the jurisdiction of the Santa Clara Valley Newell Road Bridge-Type Selection 3 SJB036700

7 Water District (SCVWD), CPA, EPA and the San Francisquito Creek Joint Powers Authority (SFCJPA). SFCJPA is currently conducting a study which identifies potential channel and bridge improvements that are needed to provide 100 year flood protection to the surrounding area. The predominant reason for replacing the existing bridge is to increase the hydraulic capacity of the SFC through the Newell Road crossing. Overhead utilities run along the south side of Woodland Avenue (EPA side) parallel to the creek. Two joint utility poles are located at opposite corners of the bridge. These utilities poles will need to be relocated as a part of the bridge replacement project. Existing steel electrical conduits attached to the downstream face of the existing bridge, which carry television cable, will also require relocation. An eruv (Jewish symbolic feature) exists adjacent to the bridge. The integrity of the eruv must be maintained during the bridge replacement project and will also need to be relocated as part of the project construction. The proposed replacement bridge will be 45.5 feet wide by 86 feet long structure containing two 16-foot wide shared lanes (11-foot vehicle lane and 5-foot bike lane/shoulder) and two 5-foot sidewalks. The new clear span between abutments of 76.7 feet measured perpendicular to the channel matches the distance between the top of the SFC banks, thus allowing the new abutments to be constructed outside of the creek s waterway including high flow events. The Newell Road Bridge is within the SFC study area for proposed channel and bridge improvements that will alleviate flooding issues and provide 100-year flood protection. An initial construction project is currently being designed downstream of Newell Road at the US 101 / SFC crossing. The design of the US 101 crossing is based on the SFC 100-year flood protection study and is currently at the 50% complete level. In order to provide adequate clearance and convey the Q100 storm flow at the Newell Road crossing, the road profile elevations will need to be raised on both Newell Road and Woodland Avenue. PROJECT ALTERNATIVES Three project alternatives have been evaluated for the replacement of the existing Newell Road Bridge: Pedestrian/ Bicycle Bridge Vehicular Bridge on Exiting Newell Road Alignment Vehicular Bridge on Realigned Newell Road Alignment Pedestrian/Bicycle Bridge (Design Alternative 1) This alternative consists of replacing the existing vehicular bridge with a pedestrian/bicycle bridge. This option was identified as a possible project alternative based on comments received at the initial public outreach meeting for the Newell Road Bridge on June 27, At first review of this pedestrian/bicycle bridge option, it is apparent that this type of a structure does not meet the stated purpose and need of the project, as described in Section 1 of this report, which is to provide a new vehicular bridge at the Newell Road crossing of SFC. Rather than dismiss this option for not meeting the purpose and need, however, the CPA and EPA authorized a traffic study to determine the impacts to the local traffic pattern if the replacement bridge was Newell Road Bridge-Type Selection 4 SJB036700

8 constructed as a pedestrian/bicycle bridge (Ref. Traffic Evaluation of the Newell Road Bridge Replacement Project report prepared by TJKM Transportation Consultants dated September 17, 2012). A copy of the traffic evaluation report associated with this study can be found in Appendix G of this report. The study revealed that the predominant movement of vehicles during peak traffic periods was from the local CPA neighborhoods to University Avenue. The study also concluded that closing Newell Road to vehicular traffic across SFC would divert the 3020 vehicles per day currently crossing the existing bridge to local non-collector residential streets in the CPA including Hamilton Avenue, Center Drive, Lincoln Avenue, Crescent Street, and Chaucer Street. The increase in traffic to these residential roads would create a negative impact to the local community and push traffic to intersections along University Avenue not currently designed for the predicted increase in traffic volumes. As a result of the traffic study conclusions and the fact that the pedestrian/bicycle bridge does not meet the stated purpose and need of the project, the Pedestrian/Bicycle Bridge option has been dropped as a viable alternative for the replacement of the existing Newell Road Bridge. Vehicular Bridge on Existing Newell Road Alignment (Design Alternative 2) This alternative consists of replacing the existing vehicular bridge with a new vehicular bridge placed on the existing Newell Road Bridge alignment. This option meets the purpose and need of the project as described in Section 1 of this report and has no effect on the local vehicular traffic pattern (Ref. Traffic Evaluation of the Newell Road Bridge Replacement Project report prepared by TJKM Transportation Consultants dated September 17, 2012). As a result, this option has been determined to be a viable project alternative and has been further analyzed as described later in this report. Vehicular Bridge on Realigned Newell Road Alignment (Design Alternative 3) This alternative consists of replacing the existing vehicular bridge with a new vehicular bridge placed on a realigned alignment to create a standard four way intersection with Woodland Avenue in EPA. This option meets the purpose and need of the project as Section 1 of this report and also has no effect on the local vehicular traffic pattern (Ref. Traffic Evaluation of the Newell Road Bridge Replacement Project report prepared by TJKM Transportation Consultants dated September 17, 2012). As a result, this option has been determined to be a viable project alternative and has been further analyzed as described later in this report. ROADWAY ALIGNMENT ALTERNATIVES General Two roadway alignment alternatives were studied for the Newell Road Bridge Replacement Project. The 2 alternatives are: 1) Existing Newell Road Alignment (Design Alternative 2) 2) Realigned Newell Road Alignment (Design Alternative 3) Conceptual plans for each roadway alignment option can be found in Appendix B of this report. The roadway profile for each alternative sets the replacement bridge soffit such that Q-100 flow of SFC can pass beneath the bridge unobstructed, as preferred by the SCVWD. In order to limit the increase in the bridge s vertical profile and to reduce impacts to the local community, creek Newell Road Bridge-Type Selection 5 SJB036700

9 bank improvements extending approximately 800 feet downstream of the Newell Road Bridge, as proposed by the SCVWD to provide 100-year flood protection in this stretch of the creek, will be constructed as part of this bridge replacement project. Based on initial hydraulic modeling of the creek at the Newell Road Bridge crossing (See the Hydraulics discussion under Technical Design Data Section of this report- Option 3), the road profile will need to be raised approximately 3.5 feet above the existing profile. So as to not greatly impact the adjacent residential properties, retaining wall systems are proposed at the back of sidewalks. The maximum height of retaining wall is expected to reach approximately 4 to 6 feet in certain locations with Alternative 2 having higher walls than Alternative 3. The profile of the retaining walls will mimic that of the roadway approaches on both sides of the bridge. Railing will be required along the top of the retaining walls in order to provide pedestrian safety in areas where the vertical differential between the top of wall and adjacent ground is greater than 30 inches. Each option proposes the same roadway cross sections along Newell and Woodland Avenue which includes: Two 11-foot travel vehicle lanes Two 5-foot bike lane/shoulders Two 5-foot sidewalks, and Landscape areas Neither option will require acquisition of additional right of way to accommodate the proposed improvements. Temporary construction easements, however, will be required for each option. Existing Newell Road Alignment (Design Alternative 2) This option maintains the existing alignment of Newell Road, crosses over San Francisquito Creek, and ties into Woodland Avenue at the same location as the existing. The result is that the existing offset intersection is maintained at Woodland Avenue. The key advantages and disadvantages of this road alignment option are listed below: Advantages: Maintains familiar traffic pattern Offset intersection acts as a traffic calming device Disadvantages: Offset intersection at Woodland Avenue maintains the existing inadequate sight distance for northbound Newell vehicles to eastbound Woodland vehicles and pedestrians. Creates less distance to transition from the raised replacement bridge profile to the grade of the existing Woodland Avenue/Newell Road intersection which results in higher retaining walls along Woodland Avenue than those needed for Alternative 3. Maintains direct headlight glare into the residential property north of Woodland in EPA Maintains the indirect route for pedestrians and bicycles travelling along Newell Road Realigned Newell Road Alignment (Design Alternative 3) This option realigns Newell Road so that the intersection at Woodland Avenue is not offset. Both the north and south legs of Newell at Woodland align and form a more traditional 4-way intersection. The replacement bridge crosses San Francisquito Creek west of the existing bridge. The realignment of Newell Road is achieved by introducing a horizontal curve in Newell Road prior to reaching the creek. The key advantages and disadvantages of this road alignment option are listed on the following page: Newell Road Bridge-Type Selection 6 SJB036700

10 Advantages: Eliminates offset and establishes more traditional 4-way intersection Creates a safer interaction between vehicles and pedestrians by creating an intersection with more familiar movements Provides better sight distance for northbound Newell vehicles to see eastbound Woodland vehicles and pedestrians Allows for more distance to transition from the bridge to Woodland Avenue/Newell Road intersection which results in lower retaining wall heights along Woodland than those needed for Alternative 2 Eliminates direct headlight glare into the residential property on east side of Woodland Provides a more direct route for pedestrians and bicycles to the future EPA Highway 101 overcrossing structure Disadvantages: Impacts the residential backyard in southwest quadrant of project in CPA. A portion of this yard is currently within the CPA s right of way in a revocable City easement. Eliminates traffic calming resulting from offset intersection thus requiring new traffic calming measures to be installed Road Alignment Recommendation In comparing the advantages and disadvantages of each design alternative, Alternate 2 has more disadvantages than advantages and Alternative 3 has more advantages than disadvantages; thus the realigned Newell Road Alignment, Design Alternative 3, is the preferred option. Alternate 3 is preferred for the following reasons: Results in a safer and more traditional 4-way intersection. Improves sight distances for vehicles at the Newell/Woodland intersection Results in a more direct route along Newell Road for pedestrians and bicyclists Results in lower retaining wall heights compared to Alternate 2 thus has a less visual impact to the local residents BRIDGE ALTERNATIVES General The CPA has indicated that the preferred width of the travel way between curbs on the replacement bridge structure is 32 feet with 5-foot sidewalks on each side. With a 32-foot width no parking will be allowed on the bridge. A standard Caltrans Type 80 SW barrier and sidewalk combination is proposed for the replacement bridge which will result in a total overall minimum bridge width 45 feet -6 inches. In addition to the sidewalks proposed on each side of the bridge, pedestrian overlooks are also proposed at the center of the span on each side of the bridge. Newell Road Bridge-Type Selection 7 SJB036700

11 Structure Type Analysis As described in the Hydraulics discussion under the Technical Design Data Section of this report (Option 3), the deck of the replacement bridge must be raised approximately 3.5 feet to pass the Q-100 flow without pressure. In order to minimize the change in deck profile elevation, structure types with a thin superstructure depth are required. Two bridge types that satisfy this requirement are: 1) Cast-in-Place Post Tensioned Concrete Slab 2) Pre-Cast Pre-Stressed Hallow Core Concrete Slab No other structure types will satisfy the minimum depth requirement at a moderate cost. Each structure alternative would have to be designed for buoyant uplift forces if the crossing requires pressure flow of the SFC Q-100 flow (Not currently recommended). Setting the replacement bridge elevation to pass the Q-100 flow without pressure, as preferred SCVWD, does not meet the Caltrans standard of providing 2 feet of freeboard above the Q-50 flow. The bridge deck would need to be raised an additional 6 inches to achieve this which would cause additional road approach work, higher retaining walls, and an unwarranted impact to the local area. Both the SCVWD and the SFCJPA require bridge crossings to provide clearance above the Q-100 flow but do not have a freeboard requirement above the 50-year storm flow. Thus a Caltrans design exception will be needed to allow the replacement bridge to infringe on the Q-50 2-foot freeboard requirement (current freeboard above the 50-year event is approximately 1.5 feet). It should also be noted that if no other alternatives are available, the SCVWD would allow a pressure flow condition for the Q-100 event if channel floodwalls are provided. Passing the Q- 100 flow under a pressure flow condition allows the bridge to be lowered by approximately 2.5 feet. A design exception from the SCVWD and the SFCJPA, however, would be required. See the Bridge Hydraulics and Evaluation or Proposed Alternatives Technical Memorandum included in Appendix F of this report. Regardless of hydraulic concept (pressure flow or no pressure flow), the need to minimize the structure depth will be satisfied by the selection of a clear span concrete slab structure that is either precast or cast-in-place. The table on the following page lists the two concrete slab bridge types and provides a description of the key advantages and disadvantages for each structure type. Newell Road Bridge-Type Selection 8 SJB036700

12 Concrete Slab Bridge Types Bridge Type Advantages Disadvantages Cast-in-Place Post-Tensioned Concrete Slab Bridge Provides the minimum structure depth allowing maximum flow clearance with the least effect on the roadway surface elevation Has the least expensive option with an estimated average cost of $225 to $275 per square foot Requires falsework in the channel during bridge superstructure construction lengthening field construction time. Allows both horizontal and vertically curve geometrics to be formed on the structure as well as forming of special geometric layouts such as the proposed overlooks Pre-Cast Pre-Stressed Hollow Core Slab Bridge Temporary falsework within the channel is not required for superstructure construction Reduced field construction time because the superstructure spans can be precast off site during the time the abutments are being constructed in the field The superstructure requires a 3 inch asphalt or polyester concrete overlay as the final wearing surface increasing the overall structure depth above the 2.5 feet needed for the cast-inplace post-tensioned slab. The thicker superstructure depth increases the vertical profile of the replacement bridge above the currently anticipated 3.5 feet More expensive that the cast-inplace post-tensioned slab with an estimated average cost of $275 to $330 per square foot Difficult to form horizontal or vertical curves with the precast slab units Cannot form the proposed overlooks Newell Road Bridge-Type Selection 9 SJB036700

13 Bridge Type Recommendation Based on the above comparisons, the cast-in-place post-tensioned concrete slab superstructure is the recommended bridge type for the Newell Road Bridge replacement structure. This structure type is the least expensive, provides the lowest deck elevation possible, and accommodates the construction of the proposed pedestrian overlooks. See Appendix C for the conceptual General Plan of the recommended Cast-in-Place Concrete Post-Tensioned Concrete Slab Bridge. BRIDGE AESTHETICS The elevated bridge profile will be visible from the westbound direction of Woodland Avenue. The roadway profile requires the use of a prominent vertical curve resulting in an arch-like bridge vertical alignment. The resulting aesthetic enhancement will add to the visual quality of the new bridge. The use of Type 80SW barriers are recommended as an additional aesthetic enhancement. The Type 80SW barrier provides vehicular safety as well as 5-foot long by 11-inch high openings spaced at 6-foot 4-inch intervals placed above the sidewalk curb, approximately 1.5 to 2.5 feet above the road surface, to provide the driver with an open feel to the bridge. The space of the openings will be filled with impact resistant glazing to preserves the full height of the opening for viewing, while providing the 4-foot FEMA required freeboard above the Q-100 water surface elevation. Fluted lighting standards are also proposed on each barrier. These standards have been traditionally used in other parts of Palo Alto. The Type 80SW has a standard lighting support on the barrier exterior that does not encroach on the sidewalk. As an additional aesthetic enhancement, each sidewalk is proposed to have a curved 16 foot wide overlook at the mid-span of the bridge that extends 7 feet out beyond the edge of deck. Further considerations of aesthetic features will be undertaken after the preferred bridge type is selected and an artist is brought on board by the CPA. These features will include further refinement of aesthetic layout, evaluation of concrete colors, textures and aesthetic concrete sidewalk finishes, and add the needed art element to the project. Conceptual bridge aesthetic renderings have been provided in Appendix D of this report. TECHNICAL DESIGN DATA Roadway Design Parameters and Criteria The following parameters and criteria were used in the development of the roadway alignment alternatives: Design Parameters: o Design Speed: 20 mph o Stopping Sight Distance: 115 o Q-100 WSEL: o Minimum Soffit elevation: o Roadway: 44 wide, (2 11-foot lanes, 2 5-foot bike lanes/ shoulders, 2 5-foot sidewalks) Horizontal Alignment: Newell Road Bridge-Type Selection 10 SJB036700

14 o AASHTO, Page 3-55 and Table 3-13b, Page 3-55 Minimum radius with standard crown section (2.0%) slope: 107 (No super elevation) Vertical Alignment: o AASHTO, Exhibit 3-71, Page 3-152; with a V=20 mph; S>L o Minimum Length of Crest Vertical Curve (Stopping Sight Distance): L=2S (2158/A) or Minimum Length of Vertical Curve = 3V, o Minimum Length of Sag vertical Curve (Stopping Sight Distance): L=AV2/46.5 Roadway Drainage Roadside drainage along Newell Road will primarily be conveyed via curb and gutter and into existing storm drain inlets. This drainage pattern for the proposed improvements is consistent with the current pattern in the area of the Newell Road crossing of San Francisquito Creek. The existing roadside drainage along Woodland Avenue within the EPA City limits will require modifications. The changes to roadway profile of Woodland Avenue will require the installation of a new drainage inlet east of the replacement bridge, at the low point created where the new road profile intersects existing. The inlet will be connected via a pipe to the existing storm facilities at Woodland Avenue and/or Newell Road. Bridge Structure Criteria Summary JOINTS AT ABUTMENT: FUTURE WIDENING: None None TEMPERATURE RANGE: 18 F to 110 F DRAINS: None on structure APPROACHES: AC pavement. Structure Approach Type EQ (10) to be provided if diaphragm type abutment is selected. SPANS: 85' - 11 ½ " (Alternative 3 Preferred Alt) STRUCTURE DEPTH: 2-6 DEPTH / SPAN RATIO: 0.30 VERTICAL CLEARANCE: 22 ± TEMPORARY VERTICAL CLEARANCE: N/A Newell Road Bridge-Type Selection 11 SJB036700

15 Bridge Design Criteria and Loading The following criteria will be used in the design of the replacement bridge: Caltrans Bridge Design Manuals o Bridge Design Specifications o Bridge Memo to Designers o Bridge Design Details o Bridge Design Aids AASHTO LRFD Bridge Design Specifications With Caltrans Addenda (Fourth Edition) Caltrans Seismic Design Criteria The flowing design loading will be used: Caltrans LRFD Vertical Loads o Dead Loads o Live Loads HL-93 Permit Loading Alternative Vehicle Seismic Forces as Specified by: o Caltrans Seismic Design Criteria o Caltrans Memo to Designers Manual Bridge Foundation Type Post-tensioned structures, such as the recommended post-tensioned concrete slab bridge, require the use of abutments that allow for both temperature movement and long term pre-stress shrinkage. Per the recommendation specified by Parikh Consultants Inc. (PCI) a pile supported foundation will be required for the replacement bridge (See the Preliminary Geotechnical Information Memo for the Newell Road Bridge Replacement (Br. No. 37C-0223), Cities of Palo Alto and East Palo Alto, CA prepared by PCI and dated July 287, 2012 Appendix E). Both driven and cast-in-drilled-hole concrete piles are possible. Cast-in-drilled-hole piles are preferred in residential neighborhoods because their installation does not include pile driving noise or cause vibration to the surrounding ground. In addition, overhead construction clearance requirements for the drill rigs are less than that needed for a pile driving crane. The site soil conditions will provide adequate vertical load capacity for either pile type. However, a relatively high ground water table and sandy soil layers may require use of temporary steel casing and use of a wet installation procedure that allows the placement of concrete below water which will increase the cost of cast-in-drilled hole piling. According to PCI, there is a possibility of some lateral bank spreading during earthquakes from liquefaction of the existing sand layers. This may cause increased soil design pressure on the abutment walls and piles. To minimize these affects and still provide for superstructure movement, the use of a diaphragm abutment on a sliding bearing will be considered during final design. This option will be compared to the more common seat type of abutment. Until more Newell Road Bridge-Type Selection 12 SJB036700

16 refined foundation recommendations are developed (to be done during the final design process), the preliminary design of the bridge and associated bridge general plan have been developed assuming a seat type abutment supported on cast-in-drilled piling will be used. Bridge Railing Type A standard Caltrans Type 80 SW barrier and sidewalk combination is proposed for the replacement bridge. The Type 80SW barrier provides vehicular safety as well as 5-foot long by 11-inch high openings spaced at 6-foot -4-inch intervals placed above the sidewalk curb to provide the driver with an open feel to the bridge. The space of the openings will be filled with impact resistant glazing to preserves the full height of the opening for viewing, while providing the 4-foot FEMA required freeboard above the Q-100 water surface elevation. Future Widening No future widening of Newell Road is proposed. Newell Road is to remain a two lane urban collector. Hydraulics The bridge is within the jurisdiction of both the Santa Clara Valley Water District (SCVWD) and the San Francisquito Creek Joint Powers Authority (SFCJPA). SFCJPA is currently conducting a study which identifies potential channel and bridge improvements that are needed to provide 100 year flood protection to the surrounding area. The predominant reason for replacing the existing bridge is to increase the hydraulic capacity of the SFC through the Newell Road crossing. HBP funding requirements prescribes that the replacement bridge must be protected against the 100-year flood. The typical method used is to set the minimum bridge soffit elevation such that it can pass either, the 50-year storm flow plus two feet of freeboard or the 100-year storm flow; whichever is the greater elevation. In order to meet the 100-year storm requirement, the deck of the replacement bridge would need to be set approximately 3.5 to 4.4 feet higher than that of the existing bridge. The elevation required for the 50-year storm plus 2 feet would be another 6 inches higher. Both the SCVWD and the SFCJPA require bridge crossings to provide clearance above the Q- 100 flow with no freeboard requirement above the 50-year storm flow. Raising the bridge profile higher to meet the Caltrans standard of 2 feet of freeboard above the 50-year storm flow would cause additional road approach work, higher retaining walls, and an unwarranted impact to the local area. Thus a Caltrans design exception is recommended to allow the replacement bridge to infringe on the 50-year storm 2-foot freeboard requirement (current freeboard above the 50-year event is 1.5 feet). NV5 has obtained and verified from the SCVWD hydraulic model for the channel. Various flow conditions have been run and a summary of the analysis is provided in the Bridge Hydraulics and Evaluation or Proposed Alternatives Technical Memorandum included in Appendix F of this report. The results indicate the following options for bridge deck elevations: Newell Road Bridge-Type Selection 13 SJB036700

17 Option 1 Unobstructed Q-100 Flow Passage: To allow unobstructed passage of the Q-100 flow, the replacement bridge deck elevation must be raised 3.5' to 4.4'. This option does not meet the Caltrans 50-year storm WSEL, plus two feet of freeboard, thus a Caltrans design exception is needed. Option 2 Q-100 Flow Passage Under Pressure: If passage of the Q-100 flow is allowed to occur under pressure, the replacement bridge deck elevation can be lowered 1.5 feet below that indicated by Option 1. Option 3 Unobstructed Q-100 Flow Assuming Downstream Improvements are Constructed:: If the channel improvement planned by the SCVWD extending up to 800 feet downstream of the Newell Road Bridge crossing are constructed, passage of the unobstructed Q- 100 flow can be achieved with the bridge deck lowered approximately 0.8 feet below that indicated by Option 1. Option 4 Q-100 Flow Passage Under Pressure Assuming Downstream Improvements are Constructed: If the channel improvement planned by the SCVWD extending up to 800 feet downstream of the Newell Road Bridge crossing are constructed and if the Q-100 flow is allowed to occur under pressure, the replacement bridge deck surface can be lowered approximately 2.5' below that indicated by Option 1. The preference of the SCVWD is to provide for unobstructed flow. The bridge profiles in this report are based on the deck elevation for unobstructed flow passage with the downstream improvements in place, which is Option 3 described above. Channel Slope Protection Channel slope protection will be provided to protect each abutment slope from a maximum stream flow velocity of 9.0 feet per second. The anticipated protection is rock slope protection (RSP). The size and volume of the RSP will be determined during final design. Utilities The following utility relocations or facility adjustments are anticipated: Sanitary Sewer On the Palo Alto side of the bridge along Newell Road an existing sewer manhole will be raised to grade to match the new roadway profile. No impacts are expected to sanitary sewer system on the East Palo Alto side. Domestic Water On the Palo Alto side of the bridge a 6 PVC water main runs along Newell Road and terminates at a fire hydrant on the west side of the road near the existing bridge. The water main will remain but the fire hydrant assembly will be relocated to accommodate the new roadway profile and sidewalk modifications. On the East Palo Alto side of the bridge an existing water main runs along Woodland Avenue. This line will remain in place and valves boxes within the street will be raised to grade to match the new roadway profile. Overhead Electrical No overhead electrical utilities exists on the Palo Alto side of the bridge. On the East Palo Alto side, overhead electrical poles and lines run along the Newell Road Bridge-Type Selection 14 SJB036700

18 south edge of Woodland Avenue within the proposed project limits. At least one utility pole is expected to require relocation to accommodate the proposed bridge and roadway improvements. Additional pole relocations may be required in order to accommodate clearances between the new bridge profile and the lowest power lines. Street Lights One street light on the Palo Alto side of the bridge along Newell Road will be impacted by the proposed roadway improvements and will need to be adjusted to meet the new grades. On the East Palo Alto side street lights are integral with the overhead electrical poles. Therefore, relocation will be concurrent with the overhead electrical pole impacts. SCVWD Stream Gage Facilities Gaging equipment attached to the upstream edge of the existing bridge and located on the upstream south bank adjacent the bridge will be removed temporarily and later replaced by the SCVWD. Existing Steel Electrical Conduit The 2 conduits attached on the downstream edge of the existing bridge will be temporarily relocated prior to the removal of the existing bridge and later placed within the sidewalk on the replacement bridge. Non-Utility Relocation of Eruv The existing eruv supported on steel poles crossing the south side of Newell Road will require coordination with the religious group associated with its original installation prior to a relocation process being established. Survey Monuments - Two Survey Monuments will need to be adjusted on Woodland Avenue. Right of Way No permanent right of way takes are anticipated on either sides of the bridge. The adjustment needed to the right of way on the backyard of the residence in the southwest quadrant is covered by a revocable encroachment permit with the City of Palo Alto. All of the permanent improvements proposed are within available City of Palo Alto and East Palo Alto Right of Way. Temporary Construction Easements (TCEs) are anticipated from all parcels within and adjacent to the proposed improvements. Two TCEs are expected on the Palo Alto side and three on the East Palo Alto side. Corrosive Soils Site soil and water will be evaluated for corrosion potential. Protection from corrosion will be provided as prescribed by Caltrans recommendation. Hazardous Materials An asbestos and lead paint survey will be conducted on the existing bridge as part of the project environmental clearance effort. PROJECT CONSTRUCTION METHODOLOGY Construction of the bridge replacement project will require closing the existing Newell Road Bridge to public traffic. This is true for both vehicle bridge design alternatives: Design Alternative 2 Existing Newell Road Alignment Design Alternative 3 Realigned Newell Road Alignment Newell Road Bridge-Type Selection 15 SJB036700

19 Closing the existing bridge will require detouring traffic to other existing nearby crossings; University Avenue and West Bay Shore Road. For Design Alternative 2, keeping the existing crossing open during construction is not an option. The narrow width of the existing bridge is not conducive to using staged construction because no portion of the existing bridge can be removed while still maintaining at least one lane of traffic. As a result, in order to maintain a single lane of traffic, a temporary bridge on a new alignment would be required. This effort would be costly and impact adjacent private properties. Design Alternative 3 could potentially use the existing bridge while partially building the replacement bridge. However, in order to complete the construction of the replacement bridge, the existing bridge must be removed. The time spent trying to keep traffic open in a safe manner and the additional costs in staging the construction of the replacement bridge for this alternative is greatly offset by the efficiency of and reduction in cost associated with closing the road and constructing the entire replacement bridge with a detour in-place. Newell Road on the Palo Alto side will be closed from Edgewood Drive to the existing crossing but will allow access to the southeast resident s driveway. On the East Palo Alto side Woodland Avenue will have limited public access during construction. Complete closure of Woodland Avenue would have adverse impacts on access and parking to the adjacent residential units. The contract documents will require one-lane traffic detours during construction to assure passage along Woodland during construction. The construction zone will also be established so that during off hours some parking will be made available in the area. Once the existing bridge is closed and traffic detours are in place the sequence of construction will be as follows: Remove the Existing Bridge Construct the Replacement Bridge. Falsework will be required for the cast-in-place posttensioned slab type structure recommended. It is likely that a 3-span falsework system will be adopted to reduce height of camber adjustment. Two falsework supports would then be placed in the channel. A single span falsework system is possible, especially if the seated abutment type is used, since a portion of the new footing can be used as the temporary falsework footing. Significant camber adjustment is required with single span falsework. In either case, specifications will allow the contractor to decide on the final falsework layout. Construct the Newell Bridge Roadway Approaches including retaining wall systems Construct the modifications on Woodland Avenue needed to meet the revised grade on Newell Road at the intersection of Newell Road and Woodland Avenue. Staged construction will be used for this work to maintain public traffic on Woodland Avenue Install Finished Paving Install Signing and Striping Close-out Construction Newell Road Bridge-Type Selection 16 SJB036700

20 ENVIIRONMENTAL PERMITTING Replacement of the Newell Road Bridge over San Francisquito Creek will require permits from the Army Corps of Engineers (ACOE), Regional Water Quality Control Board (RWQCB), Department of Fish and Game (DFG), and Bay Conservation and Development Commission. The following permits are anticipated: Section 404 Nationwide Permit 14 for Linear Crossings (ACOE) Clean Water Act, Section 401 Water Quality Certification Support (RWQCB) Fish and Game Code Section 1602 Streambed Alteration Agreement (DFG) Bay Conservation and Development Commission Development Permit: The San Francisco BCDC s jurisdiction includes San Francisco Bay, a 100 foot shoreline band that extends 100 feet inland from the upland edge of the BCDC s Bay jurisdiction and certain named waterways that drain into the Bay. PROJECT / BRIDGE TYPE RECOMMENDATION Design Alternative 3, Vehicular Bridge on Realigned Newell Road Alignment, is the recommended project alternative. The recommended alternative features include: Bridge / Roadway Vertical Profile: The recommended bridge and roadway profile is a profile that sets the replacement bridge soffit such that the bridge can pass the unobstructed Q-100 flow as preferred by the SCVWD. To minimize the needed increase in the vertical height, 800 feet of channel improvements downstream of the bridge location will be incorporated into this project to increase the flow capacity of this stretch of the SFC. Roadway Alignment: In comparing the advantages and disadvantages of the two roadway alternatives: Design Alternative 2 Existing Newell Road Alignment Design Alternative 3 Realigned Newell Road Alignment Alternative 3 is the recommended alternative. Alternative 3 is preferred for the following reasons: Results in a safer and more traditional 4-way intersection. Improves sight distances for vehicles at the Newell/Woodland intersection Results in a more direct route along Newell Road for pedestrians and bicyclists Results in lower retaining wall heights compared to Alternate 2 thus has a less visual impact to the local residents Newell Road Bridge-Type Selection 17 SJB036700

21 Bridge Type: The cast-in-place post-tensioned concrete slab superstructure is the recommended bridge type for the Newell Road Bridge replacement structure. This structure type is the least expensive, provides the lowest deck elevation possible, and accommodates the construction of the proposed pedestrian overlooks. Bridge Aesthetics: The recommended bridge architectural features include: Type 80SW to provide the driver with an open feel to the bridge with impact resistant glazing filling the 5' long by 11" high openings to provide the 4-foot FEMA required freeboard above the Q-100 WSEL. Fluted lighting standards traditionally used in elsewhere in Palo Alto. Curved 16 foot wide overlooks at the mid-span of the bridge that extend 7 feet out beyond the edge of deck. Further considerations of aesthetic features to the bridge will be undertaken after the preferred bridge type is selected and an artist is brought on board by the CPA. Project Construction Methodology The recommended construction methodology for the replacement of the existing Newell Road Bridge and associate roadway approach work is to close the existing bridge to public traffic, provide a detour using local streets, demolish the existing bridge, and build the replacement bridge in its entirety. The time spent trying to keep traffic open using a staged construction approach in a safe manner and the additional costs in staging the construction of the replacement bridge is greatly offset by the efficiency of and reduction in cost associated with closing the road and constructing the entire replacement bridge with a local street detour in-place. Newell Road Bridge-Type Selection 18 SJB036700

22 APPENDIX A Approved E-76 Form / PES

23 APPENDIX B Roadway Alignment Alternatives

24 APPENDIX C Bridge General Plan and Estimate

25 APPENDIX D Conceptual Bridge Aesthetic Renderings

26 APPENDIX E Geotechnical Memorandum

27 APPENDIX F Hydraulic Technical Memorandum

28 APPENDIX G Traffic Evaluation Report