Updated

Boston is preparing for a second day without union school bus drivers who walked off the job.

The drivers, who walked out Tuesday, say the city contractor they work for hasn't been honoring their labor contract.

The drivers' union, the United Steelworkers, says the walkout isn't authorized and has ordered the drivers back to work.

About 33,000 students were affected Tuesday. Many got rides with parents, police officers or free trips on Boston's public transportation system.

Mayor Tom Menino says parents should prepare for another day without buses on Wednesday. He said schools will be open an hour early so children can be safely dropped off before school.

The bus service company sought a restraining order to end the strike Tuesday. But a federal judge said it was too early to take such action since the union's leadership is trying to end the walkout.