Philadelphia’s mass transit system has reached a tentative contract deal with its largest workers union. The agreement announced Wednesday averts a strike that could have seen thousands of employees walk off the job. The one-year deal between the Southeastern Pennsylvania Transportation Authority and Transport Workers Union Local 234 calls for union members to receive a 5% raise and an unspecified pension adjustment. It also has language aimed at improving the personal safety of frontline workers, including installing bulletproof enclosures for drivers since many face violence and harassment. Union President Brian Pollitt says a ratification vote will be held Dec. 6.