San Mateo County (Map, News) - A possible strike by Amtrak employees this month would shut down Caltrain service and flood other Bay Area transit agencies and roads with tens of thousands of extra cars, although officials are cautiously optimistic that the commuter nightmare will be averted.

Amtrak, which has never had a strike in its 36-year history, has been wrangling over wage and benefits increases with nine service unions for eight years. If a contract is not hammered out, a strike would begin on Jan. 30.

Caltrain would completely shut down if the strike takes place and service between San Francisco and San Jose would come to a halt. Amtrak supplies all of the commuter line’s operating employees — about 350 union members such as engineers and conductors. Only Caltrain’s management is not employed through Amtrak.

“We would have to shut down business until the strike is over,” said Caltrain spokesman Jonah Weinberg, who added that he was optimistic that a strike would be avoided.

A shutdown would force Caltrain’s roughly 40,000 daily riders to flood other transit agencies, such as BART or SamTrans.

The roads most impacted would be U.S. Highway 101 and Interstate Highway 280, California Highway Patrol Officer Mike Davis said. If the strike lingers, commuters may begin to get frustrated with the extra traffic jams and search for alternative roads, which may affect traffic on Bay Area bridges, he said.

On a weekday on Highway 101, 199,000 cars drive through the freeway in San Mateo County; 156,500 cars in San Francisco, according to Caltrans figures. Roughly 121,000 cars drive through I-280 on a weekday in the county compared with 97,500 in The City.

BART lines that run parallel to Caltrain service would be affected, BART spokesman Linton Johnson said. SamTrans buses that stop by Caltrain stations would not be affected by a strike, Weinberg said. Commuters should strongly consider carpooling in the event of a strike, Caltrans spokeswoman Lauren Wonder said.

Of Caltrain’s 25 stations from San Francisco to Gilroy, employees are only stationed at the San Francisco and San Jose stations and picketing would likely take place there, said union official Don Griffin. Other stations only consist of waiting platforms and ticket machines, Weinberg said.

Both Griffin and Amtrak spokeswoman Vernae Graham said they were “cautiously optimistic” that a deal would be reached before Jan. 30. Griffin, spokesman for the union called the Brotherhood of Maintenance of Way, said a few unions met with Amtrak negotiators Wednesday for the first time in a while, and that others are returning to the bargaining table today.

mrosenberg@examiner.com