Months of contract negotiations between Charleston County school bus drivers and their employer, Durham School Services, haven’t been successful, and the situation became graver Tuesday with the potential for a driver strike.

The drivers’ union, Teamsters Local 509, called a meeting Tuesday of its Charleston membership, and drivers agreed 186-0 to authorize a strike should a contract deal not be reached.

“We’ve met with (Durham) 34 times, and we’re no further along now than we were when we started,” said L.D. Fletcher, president of Teamsters Local 509.

Both sides agreed bus driver pay was one of the major sticking points.

Durham has offered a raise, but drivers say that it’s not enough. Drivers also are concerned about a lack of affordable health insurance and the safety of their buses.

Contract negotiations between Durham and its Charleston drivers started last summer, and their contract expired in August. Three negotiation sessions are scheduled for next week, and no deadline for a deal has been set. Until then, Charleston school buses should continue running their regular routes.

“We’re optimistic good progress will be made there (in negotiations),” said Blaine Krage, public relations manager for Durham.

Officials were working on contingency plans to be able to continue bus service even if drivers strike. All of the district’s 386 bus routes could be involved, regardless of whether the driver is part of the union, Krage said. About 25,000 of the district’s 45,000 students ride a bus daily; Durham employs more than 400 Charleston drivers.

“Drivers could end up anywhere,” Krage said.

The school bus transportation company, which is the second-largest of its kind nationally, could go as far as bringing its national resources to Charleston, he said. That could mean, for example, borrowing drivers from elsewhere, he said.

Charleston County school leaders aren’t involved in the negotiations but have been kept apprised of the situation. The school district hired Durham in 2007 to employ bus drivers and manage routes.

“The bottom line is we expect Durham to be developing ways in which they can continue operation and services,” said Mike Bobby, the district’s chief of finance, operations and human resources.

Bus drivers in Mount Pleasant met with Durham’s local general manager last week to talk about what they said were unsafe buses. Drivers said their repair requests are ignored, but officials said unsafe buses aren’t used.

Latrisha Pringle was among the bus drivers who voted in favor of giving the union the authority to call a strike. She said she has a number of concerns with Durham, but perhaps the biggest issue is drivers’ pay.

She didn’t want the situation to come to this, but it has, she said.

“We have to do what we have to do,” Pringle said.

Reach Diette Courrégé Casey at @Diette on Twitter or 937-5546.