The bridge remained open after the 6:20 p.m. accident, according to the California Highway Patrol.
The barge has a capacity of 65,195 barrels of heavy black oil, but there was no evidence anything spilled into the water, said Coast Guard Petty Officer Anastasia Devlin. Several local and state agencies responded, and two oil response vessels were on the scene within an hour, according to the Coast Guard.
The outbound barge struck a piling of the westbound span as it was being guided from Rodeo by a tugboat.
The Coast Guard pushed the barge away from the bridge and anchored it, it and was investigating the incident Thursday night.
Fog limited visibility in portions of the Bay Area on Thursday night, although it was not clear whether that played a role in the accident. Visibility was three miles at Oakland International Airport and a mile and a half at San Francisco International Airport, said meteorologist Steve Anderson of the National Weather Service.
It was the Bay Area's second maritime bridge accident in two months, coming after the Cosco Busan cargo ship struck a Bay Bridge abutment in heavy fog Nov. 7.
That accident tore a gash in the ship's hull and spilled 58,000 gallons of thick bunker fuel. The spill killed hundreds of birds, temporarily closed beaches and delayed the start of the Dungeness crab and other fishing seasons.
The Cosco Busan was carrying about 1 million gallons of fuel at the time.
The disaster was followed by investigations, lawsuits and legislative proposals to improve oil spill safety because it exposed shortcomings in spill prevention and response.
A bar pilot who was aboard and advising the cargo ship's crew at the time surrendered his federal license to the Coast Guard after investigators found in his file what was described as evidence of physical incompetence.
The state finished retrofitting the five-mile-long Richmond-San Rafael Bridge in 2005, replacing 63 deck sections and more than 700 expansion joints.
The eastbound and westbound lanes run side-by-side in Richmond and on the Marin County side, merging into a double-decker span in the middle of the Bay.
Reach Scott Marshall at 925-945-4782 or firstname.lastname@example.org.