Temporary closure of lower Alpine Road Trail begins August 28

A section of Alpine Road Trail between the lower Alpine Road Trailhead and Crazy Pete’s Road in Portola Valley will be closed to all public access beginning Monday, August 28, 2023. The trail is anticipated to reopen in winter, 2023.

Midpen is completing improvements to the Alpine Road Trail in partnership with San Mateo County. Work includes improving drainage and installing retaining walls to address erosion, stabilize the trail and ensure long-term public access.

The Alpine Road Regional Trail Improvement Project was identified as a top 10 priority in Midpen’s community-supported Vision Plan. The project addresses two large failures and improves surface drainage to prevent further road degradation and to protect Corte Madera Creek. The repaired trail will re-establish Alpine Road as a regional trail multi-use connection in some areas while retaining a drivable section for critical fire and emergency access.

Phase 1 of project was completed from summer to fall of 2022. It involved repairing the southern portion of the dirt road to a 12-foot road width from Page Mill Road to Meadow Trail. From Meadow Trail to Portola Valley, it converted Alpine Road to a 6-foot-width trail.

Phase 2 of the project will commence in August of 2023. A section of Alpine Road between the Bypass Trail and Crazy Pete’s Road will be closed while Midpen is working on the lower Alpine Road retaining wall project. Two retaining walls will be built at this section to address erosion, drainage, trail bed stability and hillslope stability. The project will also repair erosion and a landslide that washed out a section of the Lower Alpine Road Trail during the winter 2023 storms.

Additionally, a new bypass trail with a more sustainable alignment will be constructed to replace the existing informal bypass trail. It will be approximately 2,500 linear feet long and four feet wide. During construction, the existing informal bypass trail will remain open. However in spring of 2024, when the new bypass trail has settled over the winter season and is ready to be used, the old informal bypass trail will be closed and allowed to naturalize.