December 29, 2015

Revised Afternoon Commute Lane Management

A new lane configuration is coming to the Golden Gate Bridge in January 2016, which is expected to improve traffic flow in both directions.

First, some background. Since September 2015, the Bridge has been configured with 4 lanes northbound and 2 lanes southbound (4 North / 2 South) between 4 pm and 6 pm, Monday through Friday. This was part of a pilot program intended to alleviate congestion on the Bridge. During those months, Bridge management reviewed real time traffic data including travel times, vehicle counts, and traffic back up distances. They determined that while congestion was reduced for northbound drivers, it increased significantly for southbound drivers. At the afternoon commute peak, there were about 4,500 vehicles per hour headed southbound and 5,400 vehicles per hour headed northbound. The lane change did improve traffic conditions on roads leading up to the south end of the Bridge, which allowed San Francisco streets to become less gridlocked.

Bridge management determined that the current 4 North / 2 South lane configuration is most helpful in traffic management on Thursday and Friday afternoons, when there is an increase in the number of drivers leaving San Francisco. This configuration will be maintained on those days only, and for a shorter period of time, from 4:30 p.m. to 5:30 p.m. (Please note that it takes 30 minutes for the zipper trucks to complete a lane change, which means the diversion will start at 4:00 p.m. and complete at 6:00 p.m.) On Monday through Wednesday afternoons, the lane configuration will be set for 3 North / 3 South.

This new configuration is intended to balance wait time for all drivers, relative to the traffic demand in both directions.

“The bottom line is that at the peak of afternoon commute traffic, there are about a thousand more drivers than the Bridge can handle,” says Kary Witt, Bridge Manager. “We have six lanes. When they’re packed to capacity, backups are going to build and drivers will have to wait. We’re working to make that wait as equitable as possible for drivers in both directions.”

Here’s the schedule in grid form for the new afternoon commute across the Golden Gate Bridge beginning January 4th, 2016.

Monday 3 North / 3 South
Tuesday 3 North / 3 South
Wednesday 3 North / 3 South
Thursday 4 North / 2 South from 4:30 p.m. - 5:30 p.m.
Friday 4 North / 2 South from 4:30 p.m. - 5:30 p.m.

The District will once again monitor the traffic impacts of these changes and will review the data in April 2016.