WASHINGTON — The construction of the Herndon Metro Station is closing a car lane at the Herndon-Monroe Park & Ride for about a month.

The Fairfax County government says that the west car lane in the bus-traffic loop at the Park & Ride will be closed while water lines for the future station are installed.

Project officials say that drivers can’t get onto the Dulles Toll Road from the facility. They say drivers are getting into the bus-only lanes, which causes safety problems.

They say drivers who want to get on the Dulles Toll Road should exit the Park & Ride facility and turn left onto Sunrise Valley Drive, then turn left onto the Fairfax County Parkway and take the exits to either the eastbound or westbound Dulles Toll Road.

Work is expected to take until early June.

More than 1,700 people park at the Park & Ride on weekdays, the county government says, and most of them board a Fairfax Connector bus to the Wiehle-Reston East Metro Station.