Tucson public transportation users may experience delays in service as many Sun Tran employees abandon the wheel and take to the streets.

Union leaders organized a strike for Sun Tran bargaining unit employees, including drivers, mechanics and service island attendants, after the Teamsters Local Union 104 rejected the Sun Tran’s most recent contract offer.

Teamsters Local Union 104 has filed unfair labor practice charges against Professional Transportation Management Inc., and about 530 union members are picketing at the Ronstadt Transit Center.

The strike, which began Thursday, Aug. 6, is the result of several frustrations union workers have with Sun Tran.

“I think employees are fed up with [having] no money and no safety,” said Andrew Marshall, the principal executive officer for Teamsters Local Union 104.

The union cites a mold problem in a Sun Tran maintenance facility, faulty financial budgeting and safety concerns due to numerous assaults on bus drivers as reasons for the strike.

“We believe that [the strike] will absolutely have to result in the mold contamination of the north facility being finally and completely wiped out,” Marshall said. “For the health of the workers there, and also the health of the public, because that mold contamination has migrated onto some of the buses.”

However, the subject of wages is a significant factor behind the strike. While Sun Tran maintains that nearly half of coach operators receive an hourly pay of $19.22, the union claims that more could be done to raise pay.

In 2014 an independent audit of the company’s finances revealed that Sun Tran returned $2.2 million to the city during the years of 2013 and 2014, which Teamsters Local Union 104 argues was specifically allocated to raise wages.

Sun Tran officials disagree.

“The monies that they are referring to were specifically allocated for the expansion of service with [Regional Transportation Authority] money,” said Kandi Young, the director of marketing and communications for Sun Tran. “That service was not implemented, so the money that was allocated in the budget to implement the service could not be utilized for anything other than what it was budgeted for.”

Another issue that has union members concerned is safety.

Within the past 13 months there have been 22 assaults on Sun Tran bus drivers, including the stabbing of a driver. Sun Tran cites that assault charges also include being spat on and having a drink or pass thrown at bus operators.

Marshall noted that while Sun Tran has made attempts to ensure coach operators’ safety by conducting trainings and placing police officers on several routes, more measures need to be implemented.

As a result of the strike, many bus routes have been put on a limited weekday service between 6 a.m. and 6 p.m.Beginning Monday, Route 4 will join the list of seven other routes that have been affected. A complete list of the limited weekday service schedule can be found on Sun Tran’s website.

“At this point we are hoping that [negotiations] can resume very quickly and that a resolution can be made,” Young said.