The Metro board discusses what caused the July 3 track derailment and train evacuation incident in College Park, Md. (photo by Markette Smith/WAMU)

(Markette Smith -- Washington, DC, WAMU) More details have emerged about the July 3 train car derailment that happened during rush hour near West Hyattsville, Md.

Metro engineers inspected the tracks a day before the derailment, but say they found no warning signs. The following day, a portion of the railing buckled from the pressure of prolonged 100-degree weather. This "heat kink" caused a six-car Green line train to jump the tracks.

Now, Metro officials say the only way to prevent that from happening again is to change the way they install railing system-wide.

Dave Kubecik, Deputy General Manager of Metro Operations, says the likelihood of a track buckling increases when temperatures climb higher than 85 degrees. So now, they're trying new methods of installing rail that can withstand greater exposures to heat.

"Knowing that it's subjected to an environment of 95 and 100 degrees, you're going to have much more movement and energy that's going to have to be released or contracted," says Kubecik. "So by adopting a standard of 95 degrees neutral, basically that means that that infrastructure is designed to take more heat and it minimizes its movement."

This is the second incident of a Metro rail buckling under extreme heat this year.

The incident also prompted the institution of a new safety rule. After the train jumped the tracks, the six-car Green Line train momentarily lost power. The train operator had did not have a cell phone and had to walk to a communications outlet to alert the rail system of what happened.

As a result of the incident, Metro has instated a 5-minute rule. So now, in the case of a communications failure, if managers at headquarters do not hear from a train operator in the field within 5 minutes, then they will automatically send emergency responders.