Metro has pulled 16 of its 5,000-series cars that have braking assemblies like the one that malfunctioned Tuesday.
It's still unclear exactly what caused the mechanical failure that led to an emergency evacuation of Metro passengers near L'Enfant Plaza on Tuesday.
Metro chief executive officer Richard Sarles say it was a friction ring -- part of the braking system -- that fell off of a 5000-series Blue Line car on Tuesday and touched the electrified third rail. The incident caused sparks and smoke, causing damage to two other trains and leading the evacuation of hundreds of passengers.
On Wednesday morning, Metro inspectors took a closer look all of their 5,000-series cars, and identified 16 other cars that could have the same problematic brake assemblies. Those cars have been taken out of service while inspections continue.
Sarles says the evacuation went smoothly, but Metro has identified areas to improve upon in future emergency situations, such as better communication with passengers aboard standing trains and the need to boost the strength of radio signals in certain areas for easier communication between Metro and emergency personnel.