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Lucas Valley Road Curve Realignment



The project will realign the curve on Lucas Valley Road at milepost 5.08, just east of Big Rock trailhead in West Marin. The public safety improvement will significantly soften the sharp turn, which has been the site of several vehicle incidents over the years.

A retaining wall will be installed on the downhill side of the turn. The retaining wall will allow for the road to be shifted east, resulting in a larger and less severe curve radius, making the turn on par with other curves along Lucas Valley Road. The project also includes modifications to storm drain infrastructure and the installation of a safety barrier and guardrail.


The $1.6 million project is funded by a $1 million Federal Highway Safety Improvement Program (HSIP) grant and the County's Road and Bridge Rehabilitation Fund.

Traffic Impacts

There will be traffic impacts throughout the project. Approximately 500 feet of the westbound lane of Lucas Valley Road will be closed for the duration of the project. All vehicles traveling through the work zone will be limited to single lane, alternating access, controlled by portable traffic signals at either end of the project limits.

Roadway pullouts at mileposts 5.34, 4.97, 4.79, 4.75 and 4.53 will be used for construction staging areas. The pullouts will be unavailable for the public for the duration of the project.

Due to the physical constraints of the worksite, critical construction operations may require intermittent temporary road closures. These full closures could last from 30 minutes to four hours and would only be conducted during daytime work hours. Advance notice will be provided of any planned full closures and recommended detours. As per standard procedure, active emergency service vehicles will be allowed access.

Traffic Conditions

Expected Impact/Restrictions:
Friday and Saturday, November 12 and 13, from 7AM to 5PMPaving operationsThe full closure will be around the project site (milepost 5.08) and will apply to all through traffic (motorized or non-motorized) traveling in both directions. Travelers will need to use alternative routes. Roadway notifications will be visible in advance of the closure location.
September 11, from 7AM to 4PM.Weekend workday scheduledThe contractor will be conducting work on Saturday, September 11, during the normal project hours of operation (7AM to 4PM). The contractor will be installing the precast lagging. Traffic control and impacts will be the same as normal weekday conditions.
August 20, from 8:30AM to 3:30PM.Deliveries of supplies and equipmentMotorized and non-motorized vehicles should expect delays up to 20 minutes in both directions to safely allow for deliveries to be made to the construction site.
July 14 and July 15, all day.Soil moving work and related equipmentMotorized and non-motorized vehicles should expect delays up to 20 minutes in both directions to safely allow for construction activities.
Starting July 12 and ONGOING for duration of project.Construction activity and crew safetyWestbound lane will be closed through construction zone. All traffic will use single lane, alternating access controlled by portable traffic signals.


Project is underway. Weather permitting, construction is expected to be completed in late November to early December, 2021, weather permitting.

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