SAN DIEGO — Unionized drivers of certain Metropolitan Transit System bus routes in San Diego are scheduled to return to work Friday after they approved an agreement with their employer, First Transit, to end more than a week of service disruptions.

First Transit provides drivers for the MTS Access paratransit service and 18 of the agency’s 95 bus routes, and full service is expected to be restored Friday.

Nick Promponas, senior vice president of the company, said negotiators for the two sides worked through Wednesday night and Thursday morning to reach the deal that drivers ratified later in the day.

The drivers — members of Teamsters Local 542 — went on strike May 25 after contract negotiations with First Transit reached a standstill.

Disrupted MTS Access service and bus routes include 18, 83, 84, 870, 944, 945A, 972, 973, 978 and 979. Routes 14, 25, 88, 833, 851, 945, 964 and 965 operated with limited service over the past week.

MTS Access drivers provide 1,900 daily curb-to-curb trips that get people to hospitals, doctor appointments and regional care centers. The bus routes are generally served by mini-buses and carry around 4,300 passengers a day.

Major bus routes and the trolley were not affected by the work stoppage, according to MTS. However, Access paratransit in the North County was halted due to the strike, as was the Sorrento Valley Coaster Connection bus shuttle service, according to the North County Transit District.