A small crack to an outbound rail at the Bethesda Metro station is forcing single tracking in the area, but shouldn’t affect the evening commute, WMATA spokesman Philip Stewart said.

Red Line trains will single track between the Medical Center and Friendship Heights stations on the Glenmont-bound track for what Stewart said should be a short period of time. Metro crews are repairing the cracked rail.

As temperatures drop, cracked rails aren’t uncommon Stewart said.

Freezing temperatures force the rails to contract and can lead to cracks.