The Project would acquire Temporary Construction Easements (TCEs) for approximately 1.39 acre that is collectively located within 19 Marin County assessor parcel numbers (APNs). The Project would also acquire Permits to Enter and Construct (PTE&C) for approximately 0.93 acre that is located collectively from within 14 APNs, and the Project would acquire approximately 0.25 acre of ROW from within one APN for the purposes of Permanent Drainage Easements (PDEs) (that is, to maintain the portion(s) of the culvert(s) that would extend beyond the Caltrans ROW). Specific ROW acquisitions proposed by the Project are identified in Table 2-3 of the IS/ND.

​

Project Components Common to All Project Segments

This section discusses Project components that would apply to all segments of the Project.

​

Rehabilitate Pavement and Add New Pavement

The Project would repair the existing SR 131 roadway pavement throughout the Project footprint and add 880 feet of new pavement within the Western Project Segment along eastbound SR 131. Pavement rehabilitation would include the following:

• Removal and replacement of 0.25 foot of asphalt concrete (AC) pavement, which would be accomplished in two lifts. The existing 0.25 foot AC pavement surface layer would be removed.

• The removal and replacement limits of the AC pavement extend throughout the Project footprint along SR 131. AC pavement would extend across the entire traveled way and shoulders, from edge of pavement to edge of pavement.

​

An approximate 800-foot-long, 2- to 6-foot-wide area of the existing median along eastbound SR 131 (PM 0.74 to 0.78) would be converted to new pavement in support of a Class I bike lane proposed along the existing eastbound shoulder within the Western Project Segment. The total depth of pavement needed for the conversion of the median is 2.35 feet. Additionally, a concrete barrier would be established within the new median to separate the opposite lanes of traffic and provide a barrier between the eastbound travel way and the Class I bikeway at this location.

​

Upgrade Guardrails

All guardrails within the Project footprint would be upgraded to Midwest Guardrail System (MGS) to meet the current standard. Specific guardrail upgrades proposed by the Project are identified in Table 2-1 of the IS/ND.

​

Curb Ramps, Pedestrian Refuge Islands, and Sidewalks

Thirty curb ramps would be upgraded, eight new curb ramps would be installed, and nine mid-block crosswalks would be upgraded throughout the Project limits. Specific upgrades proposed by the Project are identified in Table 2-2 of the IS/ND.

​

Upgrade Signage

The existing lane drop signage that is approximately 150 feet west of the Reed Ranch Road/SR 131 intersection (PM 1.55) does not meet current standards and would need to be upgraded in-place as part of the Project.

​

Three crosswalk signs would need to be replaced within the Central Project Segment: (1) eastbound direction on SR 131 approximately 300 feet north of Stewart Drive (PM 1.99), (2) eastbound direction on SR 131 approximately 150 feet west of Gilmartin Drive (PM 3.01), and (3) westbound direction on SR 131 approximately 200 feet east of Gilmartin Drive (PM 3.09). These signs are not within 50 feet of their respective pedestrian crossings. Replacement plans would be coordinated with the Town of Tiburon and City of Belvedere during the PS&E phase of the Project to determine if these three crosswalk signs need to be relocated.

​

Flashing speed limit signs are proposed at the existing intersection of Mar West Street (PM 3.95) to facilitate safe pedestrian and bicycle crossings.

​

Improve Pavement Delineation

All existing left turning arrow markings within the Project footprint would be updated to the current standard of “Type III” left turning lane arrow markings, following the pavement rehabilitation along SR 131. Additionally, every turning lane would need to be updated to include two turning arrow markings.

​

Modify Electrical Systems

The Project would modify and upgrade electrical systems along the entire SR 131 corridor, including new traffic signal poles/foundations, lighting standard poles/foundations, temporary wooden poles, overhead lines, pull boxes, loop detectors, Accessible Pedestrian Signal Systems (ADA Compliance), conduit installed by directional boring, service enclosures, controller cabinet, push button, and flashing beacons.

​

The proposed traffic signal poles/foundations, lighting standard poles/foundations, push buttons, flashing beacons, and conduits would require ground disturbance. Pits (4 feet deep by 4 feet wide by 4 feet long) would be excavated near traffic signals to place a machine for directional boring. Conduits between 2 to 3 inches in size would be installed by directional boring 30 inches below the ground surface.

​

Since the existing median along eastbound SR 131 (PM 0.74 to 0.78) would be converted to new pavement in support of the Class I bike lane outside of eastbound SR 131, several types of electrical facilities would be affected, including the following:

• Two existing state traffic signals [between intersection of SR 131/East Strawberry Drive (PM 0.67) and intersection of SR 131/Greenwood Cove Drive (PM 0.81)] would be relocated as depicted on Figure 2-1 (Appendix A).

• The existing State Lighting System (in the median) would be relocated near the guardrail along eastbound SR 131 (PM 0.70).

• The existing state interconnect cable system (in the median) would be relocated to the Bay Vista Drive intersection on the northeast corner (PM 0.67).

• The City License Plate Reader System (PM 0.75) would be removed during   construction and placed in the median once construction has been completed.

​

Western Project Segment

This section describes the proposed repairs or upgrades proposed only within the Western Project Segment footprint from Tower Drive, approximately 1,000 feet west of U.S. 101 PM 0.00, to Reed Ranch Road (PM 1.52) (Figure 2-1, Maps 1 through 13).

​

Class I and IV Bikeways

Class IV bikeways constructed as part of the Project within the Western Project Segment would improve bicycle access along SR 131, from approximately 1,000 feet west of U.S. 101, PM 0.00 to approximately Trestle Glen Boulevard (PM 1.85). A Class I bikeway is proposed from East Strawberry Road (PM 0.67) to Greenwood Cove Drive (PM 0.84), to address a major gap in the overall active transportation network on SR 131.

​

Modify Intersections

Two intersections within the Western Project Segment would be modified, including the East Strawberry Drive/SR 131 intersection (PM 0.67) and Reed Ranch Road/SR 131 intersection (PM 1.55) (Figure 2-1). Intersection modifications at the East Strawberry Drive/SR 131 intersection would include the removal of the free right turn lane from East Strawberry Drive onto eastbound SR 131 and the relocation of the existing bus stop that is along eastbound SR 131 at PM 0.69. The bus stop at this intersection (PM 0.69) would need to be relocated to construct the proposed Class I bikeway between East Strawberry Drive and Greenwood Cove Drive. Relocation of the bus stop within the Project footprint would be further coordinated with transit authorities and local stakeholders during the final design phase.

​

Curb Ramps, Pedestrian Refuge Island, and Sidewalks

A pedestrian refuge island would be constructed in the median at the Bay Vista Drive/East Strawberry Drive intersection (PM 0.67). The approximate dimensions of the new pedestrian refuge island would be 30 feet long by 8 feet wide.

​

At the intersection of North Knoll Road (PM 0.25) there is currently a pedestrian crossing without curb ramps. However, an existing power line pole at this intersection creates a clear width issue for a proposed ADA curb ramp. Therefore, the Project proposes to construct a bulb out, or curb extension with a standard curb ramp to avoid relocation of the power pole. An existing driveway to a gas station, located at the corner of the intersection, would be affected by the bulb out. The driveway would also be upgraded to meet ADA requirements. A water line cover near the pedestrian crossing would be disturbed during the construction of the bulb out or curb extension. The owner of this water line is Marin Municipal Water District and Caltrans would coordinate any necessary utility locations with applicable agencies prior to Project construction.

​

Additionally, under existing conditions, there are no crosswalk facilities between Greenwood Cove Drive (PM 0.84) and Trestle Glen Boulevard (PM 1.85). The Project would construct an additional crosswalk at the Reed Ranch Road/SR 131 intersection (PM 1.55) to facilitate pedestrian and bicycle crossing of SR 131.

​

Rehabilitate Drainage Systems

Two corrugated metal pipe (CMP) culverts would be replaced as part of the Project. An existing 18-inch by approximate 55-foot-long cross culvert CMP, is along the westbound SR 131 roadway shoulder, approximately 370 feet east of Blackfield Drive (Figure 2-1, Maps 8 and 9) (PM 0.88). Additionally, an 18-inch by approximate 260-foot-long longitudinal CMP, between PM 0.87 to 0.92 (Figure 2-1, Maps 8 and 9), is along the eastbound shoulder. Both culverts are severely corroded and need to be removed and replaced by trench excavation. An estimated depth of 8 feet is needed to complete this work. Plans to replace or rehabilitate the culverts would be determined during the PS&E phase of the Project.

​

Sea Level Rise Resilience

The Project would construct an additional 320-foot concrete barrier along the eastbound SR 131 shoulder to address the existing and anticipated flooding that SR 131 experiences due to sea level rise. The 320-foot concrete barrier would be at the existing edge of pavement within the eastbound SR 131 shoulder, between approximately Greenwood Cove Drive (PM 0.88) and Cecilia Way (PM 1.00) (Figure 2-1, Map 9).

​

Central Project Segment

This section describes the proposed repairs or upgrades to SR 131located only within the Central Project Segment footprint from Reed Ranch Road (PM 1.52) to San Rafael Avenue (PM 3.24) (Figure 2-1, Maps 14 through 26).

​

Class IV Bikeway (Separated Bikeway)

A Class IV bikeway would be constructed along SR 131 as part of the Project within the Central Project Segment. The striped shoulders of SR 131 would be converted to a Class IV bikeway over a distance of 0.3 mile from Reed Ranch Road to Trestle Glen Boulevard (PM 1.55 to 1.85). No Class I bikeway is proposed for this segment.

 

Modify Intersections

One intersection within the Central Project Segment would be modified under the proposed Project. Intersection modifications required at the Avenida Miraflores/Pine Terrace/SR 131 intersection (PM 2.36) would include the removal of an existing free right turn lane and the construction of a bulb out or curb extension (Figure 2-1, Map 20). At the Avenida Miraflores/SR 131 intersection, the existing free right turn lane from westbound SR 131 onto northbound Avenida Miraflores would be removed. At the Pine Terrace/SR 131 intersection (Figure 2-1, Map 20) (PM 2.36), a bulb out or curb extension would be constructed at the southwest corner of the intersection to increase visibility of crossing pedestrians and allow for larger queuing of pedestrians at the existing crosswalks.

​

Rehabilitate Drainage Systems

At Trestle Glen Boulevard (PM 1.86), a high side gutter (approximately 400 feet long and 3 feet wide) would be constructed along the westbound edge of the shoulder, in the north-south direction. Additionally, from PM 1.87 to 1.92, the Project would replace the wall of the existing headwall and five drainage inlets located south of Trestle Glen Boulevard and 400 feet of 18 inch storm drainpipe along the westbound shoulder to properly convey exiting flows into the high side gutter. To avoid creating an unsafe condition, the existing MBGR would be removed or modified at this location. An existing utility pole and overhead sign would also need to be relocated outside of the clear recovery zone if the MBGR is removed.

​

On the northbound shoulder, 510 feet to 680 feet north of Gilmartin Drive (PM 2.90), along Tiburon Boulevard, the area adjacent to the northbound edge of pavement drains poorly. Two drainage inlets, approximately 150 feet of 18inch storm drainpipe, and minor grading of the area adjacent to the roadway would be installed and performed.

​

Eastern Project Segment

This section describes the proposed repairs or upgrades to SR 131 within the Eastern Project Segment footprint from San Rafael Avenue (PM 3.24) to the Tiburon Boulevard/Main Street intersection (PM 4.40) (Figure 2-1, Maps 26 through 36).

​

Bikeway

No bikeways are proposed within the Eastern Project Segment footprint.

 

Modify Intersections

Two intersections within the Eastern Project Segment would be modified, including the Mar West Street/SR 131 intersection (PM 3.95) and Ned’s Way/SR 131 intersection (PM 3.55) (Figure 2-1, Map 29). Intersection modifications required at the Mar West Street/SR 131 intersection (PM 3.95) include constructing a bulb out or curb extension at the southwest corner of the intersection to increase visibility of crossing pedestrians and allow for larger queuing of pedestrians at the existing crosswalks. At the Ned’s Way/SR 131 intersection (PM 3.55), yields lines would be placed in the westbound direction on SR 131.

​

Rehabilitate Drainage Systems

At the Ned’s Way/SR 131 intersection (PM 3.55), the northern portions of the intersection periodically flood during storm and rain events. To address existing flooding conditions, the Project would install two 24-inch-wide sidewalk openings at and near the gutter low points of the Ned’s Way/SR 131 intersection. These sidewalk openings would result in greater hydraulic capacity to convey gutter flow to the concrete-lined ditch and would be less susceptible to debris clogging as compared to the existing 4-inch pipes.

Approximately 37 feet of curb along eastbound SR 131 at the southwest corner of Beach Road intersection (PM 4.15) has settled and would be replaced.