Virginia Railway Express passengers will pay 4 percent more to board the commuter rail service starting July 1.

The VRE Operations Board voted unanimously Friday to enact the fare increase, said VRE spokesman Mark Roeber. The increase means riders will pay $232.40 per month or $8.45 for a single trip from Woodbridge to Union Station. From Manassas, the fare increase would mean $250.80 per month or $9.10 for a single trip to Union Station.

VRE officials say the primary reasons for the proposed increase are rising costs for its contractors that resulted in a $1.4 million shortfall for next year. VRE’s primary contractor, Keolis, which employs much of VRE’s on-the-ground staff, has a contract that’s pegged to the Consumer Price Index. Similarly, VRE pays an automatic 4 percent increase every year to access CSX and Norfolk Southern’s rail lines.

The cost of gas has also gone up, Roeber said.

Many federal employees told VRE that pay freezes and cuts have them worried about any increases, according to a summary of public meetings held on the subject. But many have said that VRE’s solid on-time performance makes it easy for them to stick with the service, especially given the alternative traveling congested I-95 or I-66.

“It echoes our feeling on this,” Roeber said of passenger worries. “We don’t want to do a fare increase, but we don’t have a much of a choice.”