Monday, July 11, 2016
Cornfield Meet Near Panhandle, Texas: How?
On Tuesday morning, June 28, the stretch of U. S. 60 leading east from Amarillo, Texas past the small town of Panhandle was quiet in the early morning sun. The flat horizon was broken only by the spinning blades of a wind farm in the distance and a towering grain elevator near the double BNSF tracks, which run straight as an arrow from Amarillo east-northeast for many miles. U. S. 60 parallels the tracks until the road nears the grain elevator, where it takes a bend southward for a quarter mile or so around the elevator and rejoins the tracks on the other side.
At about 8:25 AM, a BNSF intermodal freight train was heading west on one of the pair of tracks. At the same time, a few miles west of that train, another train was heading east—on the same track.
Railroads have faced this kind of problem ever since there were railroads. In England, the main customers of an early form of electric telegraph were railroads, who saw in it a way of coordinating train movements on single tracks carrying two-way traffic. Later, block signals were developed that turned red any time a train entered a section of track (or "block"), warning other trains to slow down or stop. The main idea of double tracks is to allow only one-way traffic on each track, eliminating any chance of head-on collisions. And most recently, a new communications and control system called Positive Train Control (PTC) has been adopted by most U. S. railways, but its implementation has been slowed by problems with radio-channel allocations and hardware issues. On June 28, PTC was not implemented in the section of tracks that run past the grain elevator near Panhandle.
So it was that the two trains that morning, each with a crew of two, met in a fiery head-on collision that is known in railroad circles as a "cornfield meet." One person managed to jump from the train before the collision. Two bodies were recovered after the accident, and as of July 10, the fourth person's body had not yet been found.
A passerby on nearby U. S. 60 made a phone video of the wreck even as it was occurring. You can see cars flying off the track, and eyewitnesses testified to the horrific noise that seemed to go on forever. A train running at speed can take up to a mile to stop after the brakes are applied, and it is not clear at this point when, if at all, the brakes were applied on either train. Many trains, including those involved in the wreck, are equipped with digital video cameras and recorders at the front and rear, but the National Traffic Safety Board spokesman in charge of the NTSB investigation said that some of these were heavily damaged. However, other data recorders on board the trains may have survived to help understand how this accident happened.
It will probably be some months before the NTSB has time to sift through the wreckage and other evidence that could show why, in 2016, it's still possible to have such an accident. As in other railroad accidents involving fatalities in the last few years, PTC could very well have prevented this one. If operating properly, the system calculates a safe maximum speed for the train at each point in its travels, and if another train is heading for yours, presumably it would put on the brakes in time to prevent a wreck.
Trains are dispatched these days by means of centralized train-traffic control centers linked to the individual trains by microwave radio. One of the dispatch centers for trains in Texas is in Fort Worth, so investigators will probably be reviewing all communications between the controllers and the two trains involved. Like air-traffic controllers, the dispatcher's word is law as far as the in-train operator is concerned. So if both trains were told they had a clear track ahead, and saw something that looked like a train in the distance, each might have thought the other one was on the other track instead of the same track. With radio control, it's not clear to me how much significance the operators attach to block signals, which should have indicated a problem in this case soon enough to prevent the accident.
As train wrecks go in the last few years, this accident was not the worst in terms of fatalities. In this space in 2013 I wrote about a commuter-train wreck in New York that killed four, and in Philadelphia in 2015 another commuter train derailed, killing eight passengers and injuring over 200. But the Panhandle wreck is disturbing because it seems to reveal a systemic problem, either with the dispatching system or training or both. Those trains never should have been on the same track heading toward each other in the first place. And once they were, it sure seems like block signals should have let the drivers know something was seriously amiss. It is likely that this accident was the product of a combination of unlikely events, each one of which by itself does not typically lead to a major tragedy.
But to know for sure, we'll have to wait for the results of the investigation. And hope that BNSF and the other railways can speed up their implementation of PTC, which promises to make cornfield meets as rare in the future as deaths due to runaway horse-drawn buggies.
Sources: I used reports on the accident from KFDA-TV in Amarillo at http://www.newschannel10.com/story/32408347/search-ends-for-body-of-conductor-killed-in-train-wreck and a video of the NTSB news conference held after the wreck at https://www.youtube.com/watch?v=mCBTmxKx2vA. A video of the wreck itself can be viewed at https://www.youtube.com/watch?v=YiPE8e-fqKU. I blogged about PTC and train wrecks at http://engineeringethicsblog.blogspot.com/2013/12/positive-train-control-and-commuter.html on Dec. 9, 2013 and at http://engineeringethicsblog.blogspot.com/2015/05/for-want-of-spectrum-allocation.html on May 25, 2015.