On Thursday, the transit agency says it has put in new safeguards to prevent this same thing from happening again. The two cables should have never come in contact.
"The cleat broke, and the cable fell off," Metro Deputy General Manager of Operations Robert Troup told the Safety and Security Committee.
The cleat is similar to a clamp which holds up the cable.
Over time, Troup said the hydraulic cable with a metal jacket rubbed against the electrical cable and wore down the insulation. That caused an arc flash that ignited the hydraulic fluid igniting the fire and a series of explosions.
"Seems to me if you saw this in your house, you would put something to avoid one thing rubbing against another," questioned Metro Board member Tom Bulger. "Is this something your eye would pick up?"
Prior to the fire though, Metro was unaware of any problems with the cleats and wasn't looking for it. The issue is unique to the 1000-series rail cars which uses hydraulic brakes. The rest of Metro's fleet has a different brake configuration.
Since the fire, Metro inspected all of its 1000-series rail cars for this same problem and has made it part of routine checks every day.
"We looked at the car where we had installation where the cleat might have been broken, or there was a potential for the cleat to be broken. We corrected those deficiencies," Troup said.
Metro found less than a dozen rail cars with damaged cleats and no other problems with worn insulation. It is also replacing the metal jacket on the hydraulic hose with a Kevlar sleeve to reduce the friction between cables should a cleat break before it is detected.
The 1000-series rail cars in question are the oldest in Metro's fleet, showing wear and tear and are due to be replaced.
"We will be glad when we replace them,” said Metro General Manager and CEO Richard Sarles. “As you know, they're being manufactured. We will see them come on the next couple of years according to the schedule. We'll be happy to see them go.”
The fire exposed other problems for Metro. In the chaos at Silver Spring, passengers at the Takoma Park station one stop away, in the height of rush hour, were left confused.
"One of our deficiencies was in getting resources to the outlying incident, in this case Takoma," Troup said. "Given the evening rush hour, we should have deployed more people to Takoma."
No one was hurt. The train was empty having offloaded the passengers earlier because of smoke. It was headed to the Glenmont rail yard to be checked, but didn't make it.
Metro didn't say how many of the 1000-series cars have been retrofitted with the new Kevlar sleeve on the hydraulic hose, but that it is in the process.
All of the trains remain in service, but Metro says there is no danger. Now that they are looking for the problem, the daily inspections and other steps Metro has taken should catch any problems before another fire happens.