A McLean woman who was arrested for allegedly striking a bicyclist with her car after driving onto the Washington & Old Dominion Trail on Saturday night is facing an additional charge for refusing a blood alcohol test, Vienna police said Monday.

Mehak Chopra, 28, appeared extremely intoxicated, refused a breath test and was unable to complete a field sobriety test after she was pulled over at about ­­­8:30­ p.m. in Vienna, close to where the trail intersects with Maple Avenue, police said.

Chopra did not explain why she apparently drove at a high rate of speed, possibly for miles, on the trail, which is often crowded with walkers and bicyclists, police said. She appeared disoriented at the time of her arrest, they said.

“She said she was coming from Mexico,” said Gary Lose, a Vienna police spokesman.

Chopra is in custody on charges of felony hit-and-run and driving while intoxicated, pending a bond hearing set for Tuesday. The bicyclist, a 65-year-old Vienna man, remained hospitalized Monday with serious but non-life-threatening injuries, police said.

Mehak Chopra. (Fairfax County Police)

Chopra is thought to have driven onto the trail in the Reston area, but the exact spot is not known, police said. They said she headed east on a section of trail that is paved and about 10 feet wide. At least five people reported close calls with the car before the bicyclist was struck near the Vienna border, police said.

The authority that administers the trail said Monday that this appeared to be the first documented case of a car striking a bicyclist or pedestrian on the trail, and they aren’t planning any changes as a result.

“This is a really unusual circumstance that we don’t see often,” said Chris Pauley, director of park operations for the Northern Virginia Regional Park Authority.

Pauley said that the W&OD once had iron gates at its 70 grade crossings that prevented cars from accessing the trail, but the gates were removed in the 1980s because cyclists sometimes ran into them and were injured. At some crossings, there are signs or flexible poles that alert drivers to the trail.

Bruce Wright, chairman of the Fairfax Advocates for Better Bicycling, said his group would not like to see the gates return but said other changes could be made.

“Signage or engineering changes that could make trail entrances more visible to drivers might help,” Wright said, although he added that he thinks the current signage is largely sufficient.

Chopra’s attorney declined to comment.