The Green Line trails that jumped the tracks during last Friday's searing heat was caused by a heat kink, officials say, and that incident is considering changing how Metro operates in high heat throughout the system.
On July 6, three cars of a Green Line train bound for Hyattsville derailed when it tried to run through a section of track warped by the triple-digit temperatures. Now, the transit agency is studying points of temperature when trains should be forced to slow down.
Train 507 - the one that derailed - was going 50 mph when it derailed, which is the normal speed for a train to be moving through the system. However, new restrictions based on heat levels could drop trains to speeds of about 30-35 mph.
"We've always considered speed restrictions in heat and we look for certain telltale signs," Metro GM Richard Sarles said. "Those telltale signs showed up just about the same time that the first heat kink showed up."
Ultimately, though, speed restrictions will mean exactly what riders think it will mean - a slowdown in service during extreme heat.