This narrated animation displays the sequence of operation of Metro trains 112 and 214, before they collided near the Ft. Totten Metro Station on June 22, 2009. The animation begins as Train 112 leaves the Takoma Park Station, about two and a half minutes before the accident. When Train 214 reaches the faulty track circuit, it is not detected by the train control system. Except for two brief periods when the speed command goes briefly to zero, indicating intermittent function of the faulty circuit, the train control system transmits an errant speed command of 55 mph to Train 112 as Train 214 occupies the faulty track circuit.
The animation shows the operator applying the emergency braking approximately three seconds after she has a full view of Train 214 and ends with a photograph of the accident.
The top of the screen shows an overhead view of the two accident trains. The blue arrow represents Train 112 and the orange arrow represents Train 214. The yellow dots on the track separate each set of track circuit segments.
The middle section of the screen shows the elapsed time, the speed commands issued to each train by the train control system, and the actual speeds of each train.
The bottom of the screen depicts a three-dimensional view riding along with the striking train, up to the point that it collided with the stopped train.
This accident reconstruction was based on information obtained from the Train 214 event recorders. The motion of Train 112 was derived from a simulation based on speed commands that the train received from the signal system, the design characteristics of the metro trains, and other evidence. The accident occurred on track owned and maintained by WMATA, and approximately 1 1/4 miles of track are shown in the animation. The accident occurred in daylight conditions; weather and visibility at the time of the accident are not shown.
The animation begins with train 112's departure from Takoma station, about 2.5 minutes before the collision.
Train 112 is being operated in the automatic mode, where the train responds automatically to the speed commands from the train control system.
At this time, train 214 is approaching Ft. Totten, and is about eight tenths of a mile ahead of train 112.
Train 214 is being operated in the manual mode-where the operator controls the motion of the train according to the speed commands from the train control system.
Notice that the speed command for train 112 varies with the position of the train ahead.
Its actual speed lags behind the speed command.
At this point, the system has brought the speed command for train 112 to zero due to the presence of train 214 ahead, and train 112 automatically begins to slow to a stop.
The lead train, 214, is on a faulty track circuit.
The speed command displays zero, and the operator of 214 begins to manually slow the train to a stop.
Because the train control system cannot detect train 214, it responds as if the track ahead is clear, and transmits an errant speed command of 55 mph.
Train 112 automatically begins accelerating to 55 mph, with train 214 stopped and undetected just ahead.
According to sight distance testing, at 470 feet apart, the operator of train 112 had a full view of train 214.
Approximately 3 seconds after the train 112 operator has a full view of the stopped train, she applies emergency braking.
Braking action was normal, but there was only enough time to slow the train a few miles per hour.