The largest union representing BART workers voted overwhelmingly last night to authorize a strike, which btw people, would take place next Wednesday if a deal isn't reached by then. The unions have called in a mediator who arrives in town today, and it was a mediator who helped hammer out an eleventh-hour deal that averted a strike in 2005. BART workers are asking for a 3% cost of living increase in their new contract, which the agency doesn't want to give them because they're facing a $250 million shortfall over the next four years and they're already going to be hiking fares in July and December. BART, for its part, is already battening down the hatches and preparing commuters for the worst.