Adam Tuss, wtop.com
WASHINGTON - Following last week's derailment on the Green Line, Metro says it will change protocol for how fast trains should be going during periods of extreme heat.
A so-called heat kink is being blamed for causing three of the six cars on a Green Line train to come off the tracks near the West Hyattsville Station during last Friday's evening rush. Dozens of people had to be evacuated from the train, and luckily no one was hurt.
A heat kink causes rails to expand and buckle out of place. In Friday's incident, a section of track longer than four football fields was affected.
When the mercury rises to extreme levels, rail agencies will often put heat restrictions in place on the external sections of the system to slow trains down.
Metro says it will now re-evaluate the temperature level for when those restrictions will need to go into place.
"Our engineers will determine it, and we will tell our staff very shortly what the parameters are," Metro General Manager Richard Sarles said after a meeting of WMATA's Safety and Security Committee Thursday.
He said a decision on the new heat parameters could come as early as Friday.
"What that means is that at a certain point, our technical people and our engineers will decide that we have to slow the railroad down. So instead of doing 50 to 55 miles per hour, they might do 35 to 40 miles per hour," said Sarles.
The train in the Green Line derailment was traveling about 50 miles per hour, according to Metro staff.
Sarles was asked if heat restrictions should have been put in place before the derailment.
"The decision was made based on what we were seeing at that time," Sarles said.
Rail lines like MARC and VRE did call for heat restrictions during the day last Friday.
Metro says even if trains were slowed down before the derailment, heat kinks still could have developed.
But Sarles admits that slowing down trains can reduce the number and severity of incidents.
Metro also discussed another incident near the College Park Station on the Green Line last week where a train lost power and riders "self-evacuated" the train onto the tracks. Metro says communication in the incident was poor and that procedures will be changed.
Investigations into both Green Line cases continue.
(Copyright 2012 by WTOP. All Rights Reserved.)