Bon Air Bridge Replacement

1 Existing Bridge
1 New Design

DESCRIPTION: Replacement of the existing Bon Air Road Bridge.

LOCATION: Bon Air Road between Magnolia Avenue and South Eliseo Drive in Larkspur.

BENEFIT: The existing bridge is slowly deteriorating due to structural deficiencies in the current span/foundation.  The design for the replacement bridge features a reduced number of bridge supports for better creek access and to reduce flooding risk, dedicated bike lanes, and protected multi-use paths for improved bike and pedestrian safety.  Replacement was deemed the most cost effective solution to the deficient bridge due the high cost and uncertain life expectancy of repair or rehabilitation. A replacement bridge is eligible for funding under the federal Highway Bridge Program.

BUDGET & FUNDING: (fully funded) FY 2017/18—$4.025M—HBP and bridge fund. Total $36.7M

$3,000,000 from City of Larkspur’s Bridge Fund

SCHEDULE (tentative): Construction start spring 2018

Bridge Mitigation Projects

DESCRIPTION: As a condition of the environmental regulatory permitting for the Bon Air Bridge Replacement project, five off-site projects were identified to help mitigate environmental impacts caused by the project. They are the relocation of the existing Piper Park dog park, restoration of this site to tidal marsh habitat, improved public pathways and provision of docks at Bon Air Landing Park and at the Marin Rowing Club; and storm water treatment along Magnolia Avenue.

2 Mitigation Zones

LOCATION: Piper Park, Magnolia Avenue between Doherty Drive and Dartmouth Drive, Bon Air Landing Park and the public dock adjacent to Marin Rowing Club on Drakes Landing Road in Larkspur and Greenbrae.

BENEFIT: The improvements will improve access to the creek, treat storm water (helping keep pollutants from reaching the bay,)  and enhance the marsh including lookouts and signs .

BUDGET & FUNDING: (fully funded) FY 2017/18—$904,800—HBP grant, Bridge Fund. Total $4,348,000

SCHEDULE (tentative): Construction to start in fall 2018