A WMATA Metrorail Kawasaki 7000 Series railcar by MW Transit Photos licensed under Creative Commons.

A Metro 7000-series Red Line train traveling towards Glenmont derailed outside the Silver Spring station on Tuesday, July 7, causing train service to be suspended between Forest Glen and Takoma through the evening. Metro personnel were able to safely evacuate the 32 passengers on board the train, and no serious injuries were reported.

The Red Line train (#108) had arrived at Silver Spring at around 11:19 am, and was following an out-of-service non-revenue train which didn’t have any passengers onboard. When the Red Line train left the station, the lead car headed in towards the pocket track, the 600-foot-long storage track between the in- and outbound tracks, while the rest of the train appears to have traveled towards Glenmont on the outer track. While the eight cars of the train remained connected, the second car derailed and “made contact with the first car.”

A Washington Metrorail Safety Commission statement issued Tuesday said preliminary information available to them “suggests the eight-car 7000-series train passed a red signal prior to the derailment.” Metrorail train operators are not supposed to operate trains past red signals except with authorization from the Rail Operations Control Center (ROCC).

Metro’s preliminary statement issued Tuesday said all infrastructure and equipment appeared to be working properly.

Metro event data reviewed by Greater Greater Washington appears to show how the derailment occurred. At 11:20:09, the ROCC controller in charge of the Red Line’s signals set a route for train 108 to continue straight past the pocket track so it would continue from Silver Spring towards Forest Glen.

The route command at 11:20:09 issued from the ROCC instructed a motor at the switch outside Silver Spring to activate and move pieces of the tracks so the wheels of train 108 would go straight, instead of curving in towards the pocket track. While this was happening, a red signal was being shown so the operator of train 108 would know not to continue.

The ROCC computer system alerted seconds later at 11:20:22 that Red Line train 108 had overrun the signal. This indicates that train 108 was moving, in violation of a red stop signal, while a switch motor moved two pieces of steel track underneath the train. The confluence of these events caused the second car of train 108 to leave the tracks, derailing the train.

WMSC officials traveled to Silver Spring and began collecting data for the investigation into the incident. “The full investigation will require interviews, data collection and review of system recordings,” the oversight body said in a statement. Additional information they plan to collect includes “level of communication, emergency response actions, amount of damage and a variety of other details.”

Why the derailment occurred is under investigation

Nearly all in-service trains since 2009 have operated in manual mode, meaning a human operator controls the train’s acceleration and braking. With the operator at the “helm,” they are the ones responsible for keeping a train stationary when the signaling system says it’s unsafe to move forward, such as at a red signal.

At red signals, but also at spots throughout the rail system, the signaling system will display a “0” on the operator console, sometimes also known as “zero speed commands.” The zero translates to miles per hour (mph) and means the train shouldn’t be moving. Operators are allowed to move their trains during this condition only after asking permission from the ROCC, and only at speeds up to 15 mph.

Red signal violations, while serious safety concerns, are not a new problem at Metro. After the Federal Transit Administration took over safety oversight in 2016 after a derailment outside East Falls Church, they issued a requirement (a “Corrective Action Plan” in oversight speak) for Metro to come up with a solution to prevent trains from moving when they shouldn’t be.

To keep operators from moving trains when they shouldn’t, Metro committed to retrofitting the 6000- and 7000-series railcars with a software change known as a “Mode Awareness Tool” (MAT). The purpose of the MAT is twofold, according to the WMSC. First, it “ensures that the train operator is aware that he or she is using [stop and proceed] mode,” and second, it “records the use of [stop and proceed] mode in the Vehicle Monitoring System (VMS).”

In short, the MAT software is a way to ensure the operator is actively engaged and confirm they want to move the train even under the zero speed command condition. Requiring input from the operator with MAT before moving the train is similar in nature to moving a train through an area of zero speed commands in automatic train operations (ATO) mode, where the operator would have to switch from automatic to manual, drive forward, and then put the train back in to automatic: both require a manual step from the operator to act as a check to verify they know the action they’re taking.

A 7000-series train console by Ben Schumin licensed under Creative Commons.

The use of the MAT tool in the 7000-series trains is simple in operation. When a train is stopped at a location with zero speed commands, Metro policy says the operator must call into the ROCC to receive permission to move the train. After receiving permission, the operator can then enter a randomized number flashing on the console into a dialog box on the console to confirm their acknowledgment.

Tuesday’s derailment shows just how limited the effectiveness of the tool can be, even when it’s installed. Metro told the WMSC in October 2019 that all 7000-series trains were equipped with the software change, yet the train involved in Tuesday’s red signal violation and derailment was a 7000-series train. In a report from November 2019, the WMSC said it was “pleased” that Metro was rolling MAT out to the entire fleet, but that they were “concerned that more effort is required to prevent the unauthorized movement of trains without speed commands.”

Would Automatic Train Operation have prevented the derailment? We can’t know for sure

Metro’s decision in 2009 to stop using automatic train operations (ATO) was a result of a fatal Red Line collision at Fort Totten. While the overarching automatic train control system, which is supposed to keep Metro’s trains safely separated, was faulted for contributing to the crash, the ATO subsystem used to automatically control operate individual trains’ acceleration and deceleration was not. Metro has made various attempts to restore ATO since, most recently in 2015 when the system was restored briefly on the Red Line.

Metro told WAMU in a 2019 statement that they weren’t actively working on restoring ATO. “A potential return to ATO has a lower priority, and we do not have a revised timeline to announce today.” At that point, the WMSC’s Chief Operating Officer stated restoring automatic train operations might be “about five to seven years down the road” but that a different control system could be in use. Upgrading could be a large, long, expensive project.

In the shorter term, the WMSC has told Metro to find ways to institute “operational improvements” with its current train control system to monitor and ensure its operators and rail controllers are properly trained to handle zero speed command conditions.

The oversight body warned that prolonged recurrence of the speed command issues could lead to operator complacency and “increase the likelihood of unauthorized train movement,” similar to Tuesday’s derailment. While the number of areas lacking automatic speed commands is unknown, the issue appears to have grown in significance since Metro’s move away from ATO in 2009.

Metro has also been required to map and inventory where zero speed conditions exist throughout the rail system and come up with a plan to correct any defects that may exist in the signaling system causing them.

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Tagged: metrorail, transit, wmata

Stephen Repetski is a Virginia native and has lived in the Fairfax area for over 20 years. He has a BS in Applied Networking and Systems Administration from Rochester Institute of Technology and works in Information Technology. Learning about, discussing, and analyzing transit (especially planes and trains) is a hobby he enjoys.