MEMORANDUM TO: CC: Jim Tomberlin, Mountain Valley Properties GR Fielding, Pitkin County Engineer Brian Pettit, Pitkin County Public Works Director Dan Cokley, SGM FROM: Lee Barger, SGM DATE: June 16, 2016 RE: Red Mountain Road Guardrail Assessment On behalf of the property owners of 155 Sabin Drive, SGM has conducted a guardrail assessment of Red Mountain Road south of (above) Willoughby Way to the owner s driveway to determine areas where guardrail may be recommended to improve the roadway users safety on this mountainous stretch of County Road 10 or Red Mountain Road. This memorandum documents the areas where guardrail would improve safety and discusses the known conflicts that would need resolution to ensure support of this project by the Board of County Commissioners. A preliminary estimate is provided for cost budgeting purposes at this preliminary, pre design level. National, State, and County Standards Guardrail is recommended by AASHTO s A Policy on Geometric Design of Highways and Streets (2011) when a clear zone cannot be achieved. A clear zone is defined as an unobstructed, traversable area provided beyond the edge of the traveled way for the recovery of errant vehicles. CDOT s Roadside Design Guide states with respect to clear zones, For low speed rural collectors and local roads, a minimum of 10 feet should be provided. Generally per CDOT, any slope 3:1 or steeper within the clear zone requires guardrail or barrier protection. In the Pitkin County Road Maintenance and Management Plan (2016) Section 1.25 states, Guardrail should be used on roads with steep side hills and cuts, on bridge approaches and along switchbacks. In mountainous terrain with a minimum 2 foot shoulder, the graded width of the shoulder in cuts may be decreased 2 feet if guardrail is installed. Guardrail shall not be closer than 2 feet to the driving surface. Guardrails shall be of a non shiny material and shall meet the standards in the latest edition of the Colorado Department of Transportation M S Standards. Further design standards can be found in the AASHTO Roadside Design Guide and other applicable standard setting publications. The mountainous terrain setting generally describes Red Mountain Road above Willoughby Way where the side slopes on the downhill side of the roadway exceed 3:1 in most places. Although guardrail may be recommended in places where unrecoverable slopes can be protected, it is often not installed in places where low traffic volumes occur, multiple vehicle accidents are rare, site constraints prevent installation, or where funding sources are limited. These are likely reasons for the lack of guardrail on these sections of Red Mountain Road today. Generally, it is placed in locations where the highest potential for sliding off the road exists, such as those existing sections near the hairpin curves. Along the straight tangent sections between curves, guardrail is typically omitted unless
a known frequency of accidents have occurred in the past. Accident information for Red Mountain Road has been requested from Colorado State Patrol but has not been received yet. Existing Conditions The following map shows the existing guardrails on Red Mountain Road between Willoughby Way and Hunter Creek Road. Existing Section 2 Existing Section 3 Existing Section 1 Figure 1 Existing Guardrail Locations Between Willoughby Way and Sabin Drive, there are three existing guardrail sections: 1 above Willoughby Way integrated into the MSE retaining wall system (designed by SGM and constructed in 2007), 2 above the Ridge Road intersection (standard design), and 3 below the Hunter Creek Road intersection. The section below the Hunter Creek intersection is a cribbed timber/rail retaining wall with guardrail posts attached to the cribbing. Figure 2 shows this existing retaining wall/guardrail system below Hunter Creek. 2
Figure 2 Timber Cribbing Wall and Guardrail System Within Red Mountain Ranch, there is a short section of concrete wall along Sabin Drive near the property s driveway that protects the downhill side of Sabin Drive. This decorative concrete wall is about 1.5 feet in height and does not meet the standard dimensional design section for traffic barriers or guardrails per AASHTO or CDOT standards. Figure 3 shows this decorative wall to the left from the driveway at 151 Sabin. Figure 3 Concrete Barrier Wall at 155 Sabin Drive Proposed Guardrail Locations From a safety standpoint, guardrail could be applied to all sections of Red Mountain Road where unrecoverable slopes are present on the downhill side of the road; which includes the majority of the 3
roadway. A few locations exist where the downhill slopes are less than 3:1 and where dense trees exist off the shoulder that would likely prevent an errant vehicle from traveling down the slope. SGM conducted a site visit to assess the proposed guardrail locations and determined which locations could be candidates for guardrail installation if various conflicts could be resolved. Conflicts noted in the field could include installation near existing utilities, installation in areas where erosion is evident, installation where asphalt clearance is narrow, and installation where property issues may exist. SGM conducted this preliminary guardrail study using GoogleEarth to generate the proposed guardrail lengths, since the roadway corridor survey data and utility information was not available. For the purposes of this study, Red Mountain Road was divided into three sections above Willoughby Way, which are depicted in the following figures. The Lower and Upper Red Mountain Road sections are located within Pitkin County, while the Red Mountain Ranch section falls under the jurisdiction of the County and the Red Mountain Ranch Homeowners Association (HOA). In the figures below, the existing guardrail and wall sections are shown in green and the proposed sections are yellow; all are numbered from downhill up. The first proposed section (Figure 4) begins above the existing guardrail section above Willoughby Way and the final proposed section (Figure 6) extends to the concrete wall by the driveway to 151 Sabin. Proposed Section 4 Existing Section 2 Proposed Section 3 Proposed Section 2 Proposed Section 1 Existing Section 1 Figure 4 Lower Red Mountain Road Section 4
Proposed Section 10 Proposed Section 9 Proposed Section 8 Proposed Section 7 Proposed Section 5 Proposed Section 4 Proposed Section 6 Existing Section 3 Figure 5 Upper Red Mountain Road Section 155 Sabin Drive Proposed Section 14 Proposed Section 13 Existing Concrete Wall Proposed Section 12 Proposed Section 11 Figure 6 Red Mountain Ranch Section Below is a table that defines the length of the proposed guardrail section, potential utility conflicts with installation, existing erosion issues, roadway clearance issues, and property conflicts. 5
Table 1 Guardrail Tabulation During the field visit, potential utility conflicts were noted based on observable overhead utility installations. The waterline serving the neighborhood and fire hydrants appeared to be on the uphill side of the road, but will need verification. Other utilities such as telephone, cable, and sewer could be present in areas. Erosion issues were noted on the downhill side along proposed guardrail section #7 only, which may necessitate a retaining wall/guardrail system design similar to the existing section #1 above Willoughby Way. Roadway width issues were evident at seven locations, where installing a 2 guardrail section could be problematic and may require a retaining wall/guardrail system be designed. The County typically requires a 20 asphalt width for emergency access, although the existing sections of Sabin Drive are 16 in width. Finally, property conflicts may exist at many of these locations due to the prescriptive nature of the Red Mountain Road right of way. The Pitkin County parcel viewer map indicates many sections of the road that are located within abutting properties. Guardrail may not be desirable to some neighbors in specific locations where it doesn t exist today. Sections that appear to be free of any property conflicts as seen in the County s parcel viewer are noted as RMR ROW. The total proposed guardrail length is 3,465 linear feet with 25 end sections required at the terminations of the rail. Some locations require extension of existing guardrail sections and we assume the existing end sections will be replaced. Preliminary Estimate of Construction Cost Based on a standard guardrail design where no additional retaining wall or shoulder stabilization is necessary, SGM has projected a cost for materials and installation to be in the $250,000 range to complete the 14 sections of proposed guardrail. This is based on 11 days of traffic control for installation and item pricing for guardrail and end sections that is double the statewide average to account for the mountain community price mark up that is common to Aspen and other resort areas. 6
Core Ten guardrail and end sections are the County standard and are also installed within Red Mountain Ranch on Hunter Creek Road, so it is anticipated that the look of this material is acceptable to the County and the HOA. Figure 7 Core Ten Guardrail Example If a retaining wall system, shoulder stabilization, or utility relocation is deemed necessary by the County (or others) in specific locations, the cost estimate will increase. Next Steps Based on a conversation with the County Engineer, the next course of action after submitting this memo to the County would be to schedule a site visit with the County Engineer and Public Works Director to further this discussion and scope the potential survey and design needs going forward. Although these installations will improve the safety of the traveling public, guardrail presents maintenance and plowing issues that will need to be worked out. Resolving issues with property owners may present a challenge but will require targeted outreach once this project moves beyond the preliminary stage. 7