Crews pulled what appeared to be a train involved in Friday's Metro derailment along the Red Line tracks through the Rhode Island station, while passengers tried to board shuttle buses. (The Washington Post)

Investigators are trying to figure out how a six-car Metro train, headed for maintenance, derailed early Friday morning in an accident that created rush-hour delays and forced the closing of a four-mile stretch of the Red Line.

The Red Line is Metrorail’s busiest and has been beset by problems and delays in recent years.

The incident began about midnight when an operator was driving the train from the Brentwood rail yard to the Greenbelt rail yard for maintenance, Metro officials said.

Two of the rail cars derailed when the front wheels of one and the back wheels of another came off the tracks about a half-mile south of the Rhode Island Avenue station, Metro spokesman Dan Stessel said.

Metro said the incident is under investigation and gave few details about how it happened.

How the Metro derailment unfolded

No passengers were on the derailed train at the time, and there were no injuries. The operator of the train was given routine drug and alcohol tests as part of Metro’s accident procedures and “placed on paid leave,” Stessel said.

Friday’s derailment comes as Metro deals with a growing list of troubles and as the agency tries to rebuild its aging and deteriorating system with a $5 billion capital improvement program. The rebuilding effort followed sharp criticism stemming from the 2009 Red Line crash at Fort Totten that killed nine people and injured dozens.

Daily riders have dealt with routine outages of the escalators and elevators, poorly lit stations and cracked platform tiles in addition to what they say is unreliable service.

In the past year, about a dozen incidents have caused delays. They included brake problems, trouble with smoking insulators, a cracked rail and a track fire. In two instances, passengers were forced off trains with no direction from Metro after the line lost power.

The transit agency has been routinely criticized by riders and watchdogs for failing to communicate effectively — and fast — on how bad the delays are.

Management has promised that it would retrain staff on dealing with incidents, provide shuttle service faster and communicate better with passengers about delays as they unfold.

In Friday’s incident, Metro sent an e-mail alert at 4:30 a.m., warning riders that rail service would be shut down between Fort Totten and NoMa-Gallaudet U and to take buses or the Green Line. Delays ranged from 10 minutes to 40 minutes.

Some riders showed up at rail stations and were surprised to find shuttle buses waiting for them at the Fort Totten and Rhode Island Avenue stations and Metro transit police officers and other employees directing them around the station. In the affected area, about 29,000 passengers board the trains on a weekday, according to Metro statistics.

It helped that it was the Friday before a holiday weekend, when ridership is typically down about 10 percent and that the agency had several hours to organize its shuttle buses before the morning rush hour.

Still, some riders found the morning confusing and frustrating.

“I’m totally turned around,” said Michelle Eatmon of Landover as she tried to find a shuttle bus to take her to her job as a nurse in a private home on 13th Street NE.

Michelle Samedy waited at Rhode Island Avenue, hoping to get to work on time near the Takoma station. “People have to go to work,” she said. “This is insane. This is stressful.”

Carlise Burton sat with her 1-year-old niece trying to get to a friend’s day care center in Northeast from her home near Morgan Boulevard.

“I’m kind of used to it with Metro having delays,” she said. “It happens every weekend where there’s something and you have to take a shuttle bus. But today, this is big-time frustrating.”

Some riders said they were surprised at how well Metro ran its shuttle bus service, considering there was a major incident.

Brian Gladden checked his watch as he waited at the Rhode Island Avenue station for a shuttle bus to take him to Union Station so he could catch a commuter train to his job in Baltimore.

“It is not really messing me up,” he said, “or at least not yet.”

At 1:35 p.m., Metro officials said they had restored service to that area of the Red Line.

Friday’s derailment caused major damage to the third rail, which powers trains, signal cables and other equipment. Stessel said signal cables were cut by the trains’ wheels and damaged for several thousand feet of track.

Based on preliminary information, Metro officials do not think the derailment was related to a problem with a particular rail car, the track or a switch on the track, Stessel said.

Officials at the National Transportation Safety Board said they were monitoring the situation. The Tri-State Oversight Committee, which helps oversee Metro safety, said it was investigating.

Workers were already scheduled to do maintenance in the area where the derailment happened, starting at 10 p.m. Friday through the Labor Day weekend.