The Cal Park Tunnel Pathway Project was a major $17 million project to rehabilitate an existing historic 1,000-foot-long railway tunnel between the communities of San Rafael and Larkspur in Marin County.

Alta Planning + Design led the pathway design and implementation portion of the Cal Park Tunnel Pathway Project. Alta and the engineering project team addressed tunnel pathway approach, pathway user public safety and security, maintenance requirements, and potential shared use of the tunnel with future rail service. The alignment will be shared by future commuter rail, and the pathway will connect to existing and proposed pathways in both communities.

Under a separate contract, Alta staff conducted additional work with private property owners and the Town of Larkspur to address tunnel access and approach issues in order to improve wayfinding and eliminate potential conflicts between regional multi-use pathway users and local circulation on adjacent office properties.