UPDATE: All DART operations were back to normal by Wednesday morning. DALLAS (CBSNewsTexas.com) — Heat may be to blame for the DART rail service delays through downtown Dallas Tuesday.

DART says they're slowing down light rail service Thursday due to high heat. Extreme heat is bad for tracks. As they heat up, tracks can expand, bend, flex, or buckle.

Another wave of unbearable heat has Dallas Area Rapid Transit riders dashing indoors to cool off. Since late June, DART has been using 18 transit centers as cooling stations, including the busy ...