This post has been updated.

Riders on the Blue and Orange lines should expect delays in their Thursday evening commutes in both directions because of a “track defect” problem, Metro officials said.

Crews are working to resolve the issue and expect it will take until 7 p.m.

Trains will single- track between Eastern Market and Stadium Armory stations, according to Metro. Riders traveling between Eastern Market, Stadium-Armory and points east should expect 20- to 30-minute delays during the peak period. Trains will depart every 10 minutes from Eastern Market on the Blue and Orange lines, headed from downtown Washington to Virginia.

Metro officials warn that stations and trains are likely to be more crowded.

The problem was discovered during a routine track inspection around 1:30 p.m. near the Stadium-Armory station, according to Metro’s chief spokesman, Dan Stessel.

Stessel said that there’s a crack in the piece of track structure known as the “frog,” which allows a train to switch from one track and divert to another. The frog, located on the aerial section of track just east of the Stadium-Armory station, has to be replaced, Stessel said.

He said the crack could have be weather-related.

Earlier this week, a dramatic drop in temperatures caused rails on the Red and Yellow lines to crack, causing delays as the cracks were repaired..

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