Caltrans must go decisively to get better traffic safety on the Bay Bridge, where half events weren't enough to prevent a fatal accident on tricky stretch of road. The skid marks at the start of the new westbound S-curve tell the story: This danger zone is catching drivers off guard.

Drivers need to slow down on a slalom course of temporary roadway, where a motor vehicle driver died when his rig shot over the side and plummeted 200 feet to Treasure Island in the predawn hours Monday. Since Sept. 8 when the S-curve section was put in use, 40-plus accidents have occurred on the football-field length of pavement.

Caltrans has posted illuminated warning signs and a summary speed limit from 50 to 35 mph in the area. But before Monday's fatal incident, the string of accidents should have motivated Caltrans to try additional safety steps. Drivers, who ignored the go-slow advisories, need more clear warnings. The signs are too late and too subtle.

Bridge planners must reorganize how to handle the bridge's heavy weight of 260,000 drivers per day. It's a challenge made extra difficult by the need to finish building of an adjacent replacement span and merge it at the juncture where the dangerous S-curve is in use. Drivers will have to navigate this precarious stretch until the new span is connected in 2013.

Caltrans announced some minor adjustments Monday, including its plan to add reflective tape to the barriers along the S-curve and additional advisories on the westbound direction. The curve is not as much of a problem in the eastbound direction coming out of Yerba Buena Island, where most drivers tend to slow down for the tunnel. Those fixes may not be enough.

Our immediate concern is for the daily hazard created by the S-turn. Drivers need to be better warned, and speeders need to be cited. As we saw Monday, it can mean the difference between life and death.