Ramps connecting U.S. Highway 101 to southbound state Highway 1 will be closed today until 11:30 a.m. while trees are removed nearby.
Motorists coming from Lombard Street or Marina Boulevard should use Geary Boulevard to get to Highway 1. Detour signs will direct southbound motorists to continue on Highway 101 to Geary Boulevard to Highway 1.
The tree removal is part of a project that will replace Doyle Drive, the 1.5-mile stretch of Highway 101 that runs in the Presidio and connects the Peninsula to the Golden Gate Bridge.
More than 100,000 vehicles use Doyle Drive every weekday, but project planners say the street is structurally and seismically deficient.
Tree removal began Aug. 11 and will continue through October. The trees must be removed to create space for the new roadway and its construction, which is slated to begin this fall.