On Saturday, June 30, 2018 at about 6:18 p.m., Washington Metropolitan Area Transit Authority (WMATA) Green Line Train 502 (T-502) headed from Greenbelt to Branch Avenue was incorrectly routed through two switches while in approach to the Fort Totten Metrorail station. The train came to rest in the non-revenue, single-track connector known as the B&E, which links the Red Line to the outbound Green Line.
The train operator of T-502 reversed operating ends of the train twice in order to move the train from the connector track back to the outbound Green Line track, then cross over to the inbound track where it should have been. This resulted in a 12-minute delay for the train’s passengers.
There were no injuries or damage during the incident. There was also no risk of a collision as, although the routing was incorrect for this particular train, it is a legitimate and viable routing; the Automatic Train Protection (ATP) system is designed to halt any conflicting train movements if any are detected.
Based on the information that is available to us, we believe the probable cause of this incident is human error on the part of both the train operator of T-502 and the Rail Operations Control Center (ROCC) staff.
The operator of T-502 failed to properly scan the tracks ahead and identify the first incorrect switch setting, which allowed the train to cross over from Track 2 (the inbound track) to Track 1 (the outbound track) on the Green Line. The second switch took the train from Track 1 to the B&E (connector track). These switches are protected by signals E06-08 (which protects movement from Track 2 to Track 1 under normal train traffic) and E06-52 (which protects movement from Track 1 to the B&E), respectively.
Both signals identified above should have been showing a ‘flashing lunar’ aspect, i.e. a white flashing light indicating that the switch is aligned for a diverging route to the other track. Additionally, the operator should have recognized that the speed commands being sent to their train indicated a reduced top speed of 28 MPH before the first switch; this speed is one of a small subset indicative of a impending crossover move, which could have alerted the operator to the incorrect routing. The operator of T-502 should have stopped the train upon seeing the flashing lunar at E06-08 and contacted the ROCC.
It is unclear why the switches were aligned for the movement T-502 took, as no trains utilized that route immediately prior to T-502. The ROCC controller should have identified earlier that the signal E06-52 was showing a proceed indication, which would be an unusual occurrence during normal operations.
Images below are from our partner DCMetroHero displaying the movements of Train 502 into the B&E Connector
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