SAN FRANCISCO (KTVU) - For the first time, the Golden Gate Bridge is closing down its northbound lanes for the San Francisco Marathon.
The lanes will be shut down Sunday between 6 a.m. and 9 a.m.
Southbound lanes will be open as usual, and bridge sidewalks will remain open to pedestrians and cyclists.
Bridge officials are citing security concerns in light of recent attacks around the world for the closures during the race.
Priya David Clemens, the Golden Gate Bridge spokeswoman says, "The Bridge Board of Directors wanted to make sure that vehicles and runners wouldn't mix on the bridge roadway. We wanted to make sure that the tragic incidents seen around the world as drivers have intentionally driven into crowds, was not repeated here at the Golden Gate Bridge."
Officials say drivers can expect significant traffic delays along the marathon route.
There will be detours as necessary.
27,000 runners are expected to take part in the 40th San Francisco Marathon.
The race takes runners on a course past Fisherman's Wharf, up to the Golden Gate Bridge and through Golden Gate Park.
For more information on the 40th San Francisco Marathon click here.