The Yerba Buena Island Detour, also known as the S-Curve, is the most significant realignment of the Bay Bridge since it opened in 1936. This new alignment requires a reduced speed limit as drivers no longer have a straight shot into or out of the Yerba Buena Island Tunnel; drivers must now pay close attention to the detour’s curves.

While the speed limit on the rest of the bridge is 50 mph, the S-curve speed limit is 40 mph for cars and 35 mph for large trucks. Several safety enhancements, including speed limit signs with flashing lights, reflective striping on barrier rails and radar signs that alert motorists if they exceed the speed limit, have been added to the detour.

Caltrans is also closing lanes during off-peak hours to allow the California Highway Patrol (CHP) to position officers to enforce these speed limits. Since that enforcement began, the CHP has issued hundreds of tickets for speeding, driving under the influence and other violations. Due to the CHP's enforcement and other efforts, drivers are slowing down and heeding the speed limits.