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. 

Positive Train Control and Commuter Lines: A Train Wreck of Another Kind

Early Sunday morning, Dec. 1, dozens of people living in Westchester County and points north of New York City along the Hudson were riding in a southbound Metro North commuter train driven by veteran engineer William Rockefeller Jr.  The scenic rail line follows the east bank of the Hudson and makes a sharp curve just north of the Spuyten Duyvil station.  According to information leaked by a union official later, Rockefeller "basically nodded" at the controls in his booth at the front of the train, which was electrically linked to the locomotive that was pushing the train from behind.  Whatever Rockefeller's state of mind was, the speed recorder recovered from the train verified that it hit the curve at 82 MPH (131 km/hr), well above the 70-MPH (112 km/hr) speed limit for the straight stretch of line north of the curve, and way too fast for the 30-MPH (48 km/hr) zone in the curve.  The result?  The locomotive and all seven cars derailed, four persons were killed, and over 60 were injured.  As bad as this literal train wreck was, it highlights a different kind of train wreck that is taking place at commuter lines across the U. S.:  one involving a federally-mandated system called Positive Train Control (PTC).

There is little doubt that if the Metro North train operated by Mr. Rockefeller had been equipped with PTC, the accident would never have happened.  As passed into law by Congress in 2010 and required in all trains by the end of 2015, PTS is a system that takes information on a train's location and automatically enforces speed limits in accordance with track regulations, operating conditions, and other factors.  (Think of it like a car equipped with a cruise control that would automatically slow you down to 20 MPH (32 km/hr) in a school zone even if you stomped on the gas.)  So even if Mr. Rockefeller had fallen asleep with his foot on the "dead-man" control (which automatically stops the train if a driver lets go of it), the train would have slowed down safely before it reached the 30-MPH zone.

So why didn't Metro North install PTC already?  Many freight lines have completed their installations, and even the Brotherhood of Locomotive Engineers and Trainmen, a union which does not happen to count Mr. Rockefeller as one of its members, has issued a call for PTS to be installed as soon as possible in all commuter trains. 

There are a couple of reasons, which can be summarized as suitability and cost.  PTC was developed and intended mainly for long-distance freight lines to prevent derailments and other accidents involving hazardous cargo.  Freight-train engineers are often on 24-hour call, and so sleep-deprivation-induced inattention is a real danger, which is one reason freight lines have adopted it so fast.

Commuter lines, with their regular schedules, frequent starts and stops, and much more dense traffic and line networks, are a different sort of problem.  While PTC often relies on GPS for some of its functions, GPS doesn't work underground, which is where many commuter lines spend a good bit of time.  It turns out that the unfunded mandate to install PTC on all U. S. commuter lines might cost as much as $2 billion, which is a lot of change for cash-strapped municipalities.  Even before the crash, many commuter lines had given notice that they were going to miss the deadline, and there was talk of legislating an extension for such lines.  But clearly, PTC was too late to help the four victims of Sunday's crash. 

Not all engineering ethics issues are clear-cut, and rail safety is one of them.  One of the first ethical cases to draw the attention of the IEEE, the largest professional organization of electrical engineers in the world, involved a commuter rail line.  In 1972, as BART, the Bay Area Rapid Transit System of San Francisco, tested its new state-of-the-art automatically controlled train cars, a non-injury accident occurred which led whistleblowers to go public with their doubts about the design.  There are similar concerns that PTC technology is not ready for commuter lines, and if fully installed would either slow down the trains so much that schedules would have to be changed, or might take automatic actions that could cause accidents instead of preventing them. 

Metro North trains already have several safety systems installed such as the "dead-man" switch, but reportedly a second type of "alerter" system, which required the engineer to respond to a beep by tapping a control every 25 seconds, was available only in the locomotive itself at the rear of the train, not in the front cab where Rockefeller was.  Investigations of many kinds of accidents often reveal that safety equipment was installed that could have prevented the mishap, but it was either not operating at the time, was disabled, or not available under the particular circumstances that prevailed. 

As the controls and software capable of replacing some, if not all, of the functions of a human driver become more available, either economic forces or the force of law will push both private and public entities to adopt them.  We are seeing this already with Google's self-driving cars, and while PTC does something close to the same thing, it has been out of the public eye until now.  But the same type of tradeoff exists for both PTC and self-driving cars.  The promise of much lower accident rates is offset by the expense and administrative headaches of implementing the systems. 

The immediate cause of Sunday's accident is pretty clear by now.  Mr. Rockefeller did the honest thing by admitting he was sleepy.  When even locomotive-engineer unions call for the installation of potentially job-threatening systems such as PTC, it's a sign that the technology's time has come.  As long as it can be adapted safely and economically to the demands of commuter lines, we can look forward to the chance that the four people who died on Dec. 1, 2013 might be the last lives lost in a U. S. train accident for many years.

Sources:  I referred to reports on the accident carried in the New York Daily News on  Dec. 5 at http://www.nydailynews.com/new-york/bronx/metro-north-engineer-sleep-disorder-article-1.1538717, a statement issued on Dec. 5 by the Brotherhood of Locomotive Engineers and Trainmen at http://www.blet.org/pr/news/newsflash.asp?id=5507, a CNN report on the crash published on Dec. 4 at http://www.cnn.com/2013/12/04/us/new-york-train-crash/, and the Wikipedia article on Positive Train Control.