An effort to improve traffic flow on Rockville Pike begat even worse traffic Wednesday, as a gas leak at the site of a utility moving project left a northbound lane closed into the evening rush.

A short stretch of a single lane of 355 northbound — between Cedar Lane and Elmhirst Drive near the Walter Reed National Military Medical Center — is shut, and officials said repairs are likely to extend through 8 p.m.

Phil Alperson, a Montgomery County official working on base relocation issues, said a variety of utilities, including telephone, electric, sewer and gas lines are being moved ahead of planned road improvements meant to address increased traffic at Walter Reed.

The cause of the rupture remains unclear, according to Maryland State Highway Administration spokeswoman Kellie Boulware. A crew was at work at the site the previous night, but was not working at the time of the leak Wednesday, Boulware said.

Authorities were notified of the leak around noon, and the gas was turned off later Wednesday afternoon, Boulware said. All lanes of Rockville Pike were closed one point, she said.

Alperson said in a statement that the leak “does not affect homes in the area,” but said Washington Gas customers can call 1-800-752-7520 with questions.