The Four Corners intersection, which serves as a complex and oft-treacherous convergence point for travelers along Panoramic Highway, Sequoia Valley Road and Muir Woods Road, has been the subject of evaluation in recent years on potential redesigns via the Marin County Department of Public Works to improve safety for access between Highway 101, Shoreline Highway, Mill Valley, and Tam Valley to Muir Woods, Mount Tamalpais, Stinson Beach, and other West Marin destinations frequented by locals and visitors alike.
An online public meeting via Zoom is set for Monday, October 30, at 6pm via to review the proposed project and provide a progress update on the short-term design. During the virtual meeting, the design team will discuss the proposed changes to the intersection layout and signage modifications to improve the circulation and safety at the intersection and welcome public comment on the proposal. Since the prior public meeting in December 2022, the design team has been working on a detailed short-term solution including lane realignment and signage plan, which is targeting construction for 2024.
Typically, the Four Corners intersection has a daily traffic volume of around 4,100 vehicles during weekdays. That number can swell to over 7,000 vehicles per day on weekends with nice weather. The goal of the project is to improve visibility and functionality for all users, including tourists who may not be familiar with the area. The project will improve configuration of the intersection, including the skewed approaches of the roadways and lane alignments. The number of cyclists and hikers either using or crossing the roadway further emphasizes the multimodal uses and the need to develop a solution that benefits all users.
Initial analysis of the intersection led to two design concepts which were presented at a community meeting that took place online in December 2022. The short-term concept was to redesign the existing lane layout approaching and through the intersection, which could be accomplished with repainting lane lines and improving signage. The long-term alternative would replace the intersection with a roundabout. In addition to needing funding for construction, implementation of a roundabout would involve extensive engineering and design work, community outreach, and coordination with surrounding landowners.