Metro has replaced more than 290 brake parts on rail cars as a precautionary measure after similar pieces broke off two rail cars in separate incidents in the past few weeks, the transit agency said Monday.
Work crews made the replacements over the weekend as they inspected 464 rail cars, which make up about 41 percent of its overall fleet. Now, Metro spokesman Dan Stessel said, the agency plans to inspect the rest of the fleet, too.
However, the agency still hasn’t determined what caused two of the “friction rings” to break off from the brake system on two different model rail cars.
“Until we can identify the cause, we are changing out any ring that shows wear,” Stessel said.
The rings, which are about two-feet-wide, resemble brake discs on regular automobiles. Each rail car has eight of the rings, Stessel said.
The problems began on Dec. 20, when one friction ring broke off a train during the morning commute, damaging two subsequent trains and trapping about 300 riders underground for more than two hours.
Metro inspected all 190 railcars of that model. But agency officials gave those rail cars a clean bill of health.
Then, another friction ring broke off a different model car, a Breda 2000 series, just before noon Friday. The incident didn’t cause the same level of damage or rider hassles, but it suggested the possibility of a broader problem.
Metro immediately said it planned to inspect all model cars from that manufacturer, which includes the 2000, 3000 and 4000 series cars. It finished the inspections over the weekend, Stessel said, and swapped out the rings showing wear even though the manufacturer’s standards suggest they can withstand more use before replacement.
The only model cars not inspected yet are the 6000 and 1000 series, the newest and oldest models in the system. Stessel said they plan to inspect the 6000 first.
The 5000 series car with the first broken friction ring had last been inspected on Dec. 8, less than two weeks before it fell off, according to Metro. Because officials are still investigating the cause, Stessel declined to release when the latest rail car had last been maintained, and whether it was inspected at the same rail shop as the first car with problems.
“We are not releasing those details at this point,” Stessel said.
