Ticket vending machines at nine Virginia Railway Express stations have been experiencing intermittent outages since Monday.

All but four had been fixed as of Thursday, officials said. Machines are still going in and out of service at the Burke Centre, Leeland Road, Brooke and Manassas stations.

The outages were caused by upgrades made to VRE’s communication system over the weekend, spokesman Mark Roeber said. Since then, “there’s been difficulty in keeping a constant communication feed,” he said.

Roeber said technicians have been dispatched to the four stations still experiencing problems.

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