Cracked rails a frequent problem on Metro

WASHINGTON — Metro says a cracked rail that slowed down the red line for several hours on Thursday was the 26th such case this year.

The Washington Examiner reports that last year, there were 49 cracked rails on the Washington area’s subway system. There were 33 in 2010, 19 in 2009 and just seven in 2008.

The latest crack occurred near the Bethesda station. Trains were forced to share a single track for about 5 hours between the morning and evening peaks.

It’s not clear what’s causing so many cracks. Metro has blamed fluctuating temperatures at times, but Thursday’s incident occurred underground, where temperatures are more stable.

Metro officials say they’re about to start using a new track-testing machine that uses thermal imaging and can pinpoint trouble spots before cracks form.