It may have been the blistering heat, although the heat was not implicated in an April Metro derailment but whatever the cause, a Metro train derailed in Prince Georges County on Friday July 6th, 2012. The incident reportedly injured none and by all accounts was responded to promptly .but concerns remain that further derailments remain a possibility
The derailment took place around a quarter to five Friday afternoon near the West Hyattsville Metro station, when a six car train carrying approximately 50 passnegers left the tracks. the most immediately postulated cause was the effect of sustained high heat on the Metro rails causing expansion.
Metro wisely ordered all above ground trains to stay beloew 35 miles per hour. The passnegers on the derailed train exited through a fan shaft at 29th Avenue and ager Road in hyattsville, Maryland. Not suprisingly, the derailment adversely effected Metro service on Metro's Yellow nd Green lines. http://www.maryland-law.com/library/metro-track-worker-safety-is-there-any.cfm
The bottom line, the June 2009 Fort Totten Metro crash with its horrific injuries and deaths has clearly made Metro both more responsive and more sensitized to the possibilities of potential disaster. For more see: http://www.wtop.com/41/2933796/Derailed-train-causes-major-rush-hour-delays and http://www.maryland-law.com/library/why-does-metro-keep-having-deadly-accidents.cfm