Station manager Alex Washington Jr. directs passengers to shuttles after a Metro train partially derailed in Prince George’s County. (JUANA ARIAS/FOR THE WASHINGTON POST)

Metro officials, responding to a botched train evacuation and a derailment three days later, said Thursday that the transit agency will institute new procedures for evacuating rail cars and will revise guidelines for service during extreme weather, like last week’s high temperatures.

The two incidents raised questions about Metro’s ability to manage emergency situations, and, on Thursday, Dave Kubicek, the transit agency’s deputy general manager of operations, told members of Metro’s safety and security committee that emergency response practices will be improved.

Kubicek said that when a train loses power, as a Green Line train did on July 3 in Prince George’s County, emergency procedures will be initiated within five minutes. Hundreds of passengers were stuck in sweltering cars after the Green Line train lost power 1,000 feet from the College Park station, and many of them ended up walking along the tracks to escape the disabled train.

But there are differing accounts of what precipitated the dangerous evacuation and how it was carried out. Metro officials maintain that some passengers, after sitting on the train for several minutes, began exiting the cars. But some passengers said they were told by a train operator that they could exit the train. Kubicek said that in interviews with supervisors, the train operator denied telling passengers they could leave the train. What is clear, Kubicek told board members, is that Metro needs a better strategy for communicating with riders.

“We have got to start mobilizing right away,” he said.

Board members said they found the communication breakdown troubling, even more than the derailment, which concluded with an orderly evacuation.

“In many ways, I’m more concerned about this” incident, said board member Kathy Porter. “We have a good capacity to deal with engineering problems, but I’m not sure we have advanced in dealing with communication and human-reaction problems.”

Kubicek said too much may have been expected from the train operator, who was rushing to determine the nature of the breakdown and communicate with her supervisors while also managing a trainload of irate passengers in extremely hot weather. Metro’s response was also hampered by a breakdown in radio communication. Officials had not realized a communication tower had lost power, hampering radio transmissions.

Committee member Tom Downs said officials must act quickly to address that shortcoming.

“Not knowing that part of our system was dark is a system capacity that needs to be addressed,” he said.

On Thursday, Kubicek offered new details about Friday’s derailment, which shut down service on a portion of the Green Line for the entire weekend. None of the 55 passengers aboard the train was injured in the incident.

Officials think that excessive heat caused a kink in the track, throwing the train out of alignment. He said that at the time of the accident the train was traveling more than 50 mph through an area with a slight curve and downgrade. He said the train operator saw an anomaly in the track and applied the brake but was unable to stop the train.

He said the stretch of track where the train derailed was inspected the day before the accident but no issues were detected.

Metro can slow trains during excessive heat spells as a precaution. No such limits were in place at the time of the derailment, but shortly after the incident, officials slowed trains to a maximum of 35 mph on above-ground sections of track.

Officials said decisions to slow trains are made on a case-by-case basis, but since Friday’s derailment, they are developing new criteria for determining when speed restrictions need to be instituted.

Metro General Manager Richard Sarles said that although reduced speeds cannot prevent heat kinks from occurring, they may enable train operators to stop a train more quickly should they spot a track issue.

The Green Line derailment was the second time in three months that one of Metro’s trains jumped the track with passengers aboard. In April, an outbound Blue Line train carrying 1,000 passengers derailed at Rosslyn.

The cause of that incident was human error — a switch was not properly clamped — and an employee involved in the incident was fired, Metro spokesman Dan Stessel said.

Safety and security committee members were also briefed on other incidents, including two in which train operators ran through red signals at Grosvenor.

Those violations took place a week apart, June 20 and June 27, and involved train operators who were relatively new to the Red Line route, Kubicek said. Both operators have been disciplined, Sarles said.