CHICAGO (CBS) — The heat was blamed for the warping of CTA track that snarled commuter traffic on the Red Line during Monday’s end-of-day rush hour.

A kink developed in the track at the Cermak/Chinatown station because of the extreme heat — the rapid transit version of a pavement blow-up. 

Problems were “significant” during the rush hour because of the close spacing of trains.  But spokesperson Sheila Gregory said that by 7:30 p.m., the single-track operation was moving smoothly, with only minor delays, with trains operating in each direction about once every 10 minutes.

Gregory said CTA track crews were expected to have repairs complete by 10 p.m.