PHILADELPHIA (AP) — Police officers for the Philadelphia region’s main transit system went on strike Wednesday, citing poor working conditions for the 178 officers that patrol stations.

Members of the Fraternal Order of Transit Police Lodge 109 walked off the job for the Southeastern Pennsylvania Transportation Authority when they said a contract presented to them “wasn’t what they told us it was going to be.”

“It’s extremely frustrating,” said Troy Parham, vice president of the union, as he and others picketed outside SEPTA’s headquarters in downtown Philadelphia. “They (SEPTA) let us believe we were almost there. At the last minute, we have to call this strike. It’s unfortunate.”

SEPTA said it does not expect the strike to affect services for the nation’s sixth-largest transportation system in terms of ridership, operating buses, subways, trolleys and trains.

The police union has been seeking a new contract to replace an agreement that expired a year ago. SEPTA said the average police officer salary is $78,706 a year.

SEPTA spokesman Andrew Busch said their strike contingency plan calls for police supervisors to work 12-hour shifts and an increased presence by city and suburban police.

Union president Omari Bervine told TV station WTXF that the union is underpaid and understaffed and that members “need to be compensated fairly.”

SEPTA and the union don’t have immediate plans to meet again, Parham said, but he’s “hoping we can resolve this soon.”

“It’s not fair to my members, it’s not fair to this union, it’s not fair to the riders on SEPTA,” he said. “It’s something we can get resolved in a few minutes.”