The Baker-Barry Tunnel, a primary route to the Marin Headlands, is closing for an extended preservation project starting Jan. 2 and may affect access to Golden Gate Bridge lookout points.
The tunnel will be closed to all users for 24 hours, seven days a week through early May, according to Golden Gate National Recreation Area officials.
Two one-day closures for pre-project inspections also are planned for December, but the dates have not been announced.
The project will repair the tunnel’s concrete structure, which contains cracks and leaks that cause a slippery film of sediment and present a safety hazard for vehicles and bicycles.
A new, brighter LED light system that will be installed in the tunnel will reduce energy use by 40 percent. Water and sewer lines, which are subject to frequent breaks causing tunnel closures, also will be replaced.
The tunnel was previously closed for several hours in August and October.
The January-May closure may cause limited access to Golden Gate Bridge overlooks. The Golden Gate National Recreation Area advises visitors to avoid traveling to the Marin Headlands during weekday rush hours between 3-7 p.m. and Saturdays and Sundays after 2 p.m.
Bridge views also are available at Fort Baker in Marin County and Crissy Field in San Francisco. Recreational bicyclists should use Conzelman Road during off-peak times or use another route.
More information, including maps and detour information, is available at http://go.nps.gov/tunnel.