Members of the Amalgamated Transit Union Local 192, which represents nearly 1,800 bus drivers, mechanics, dispatchers, clerical and other workers, voted Saturday 576 against to 257 for the proposed contract, officials said.
"Our members spoke out, loud and clear," said Yvonne Williams, the union's president and business agent, in a statement.
The union's negotiating committee will meet soon to review next steps, officials said.
The union had previously issued a notice on Monday Aug. 5th saying it would go on strike at 12:01 a.m. Aug. 7th if no progress had been made.
The deal reached the next day included a 9.5 percent raise and increased employee contributions to medical benefits, as well as improved health and safety provisions, according to the union.
An AC Transit spokesman said he had not received official word from the union yet and did not have any comment.