CALIFORNIA - BART's two largest unions said Thursday afternoon that they will not strike today, even without new contracts.

The unions agreed to give 72 hours' notice before a walkout, but that pledge expired at the same time as the contracts - midnight Thursday.

Union leaders said they would give reasonable notice before a walkout.

"Reasonable is more than an hour's notice, more than a day's notice, I would hope," said Lisa Isler, president of the BART chapter of the Service Employees International Union, Local 1021, which represents BART mechanics and clerical workers and accounts for about half the rail agency's 2,800 unionized workers.

She and Jesse Hunt, president of Amalgamated Transit Union, Local 1555, which represents close to 900 BART employees, including train operators and station agents, said they will not walk out today.

"The commuters do not have to worry about" today, Isler said Thursday.

BART has about 355,000 boardings a day. The last strike, in 1997, crippled the Bay Area commute.

Hunt said he hopes that talk of a strike will be moot.

"At all levels, progress is being made," he said.

The negotiators were still at the bargaining table Thursday night.

BART management spokesman Linton Johnson said as long as progress is being made, "we're willing to stay at the table."