Showing posts with label railroad safety. Show all posts
Showing posts with label railroad safety. Show all posts

Monday, January 13, 2020

Death Rode the Rails, Indeed


The prospect of dying in a railroad accident is not something that too many Americans worry about these days.  But it was not ever thus.  In an excellent but little-known book entitled Death Rode the Rails:  American Railroad Accidents and Safety 1828-1965, economic historian Mark Aldrich reveals that in the earliest days of rail travel in the 1840s, passengers were sometimes surprised to see a thin strip of iron thrusting up through the floor of the carriage, threatening to impale them like bits of beef on a barbecue skewer.  Called "snakeheads" by the antebellum press, relatively few people were killed by these accidents, which occurred because some of the earliest railroads used a thin iron strap fastened to a wooden rail to save money, instead of a solid iron rail, and the strap would sometimes come loose from the wood, snaking its way up into the cars.  But the combination of surprise and powerlessness to avoid the accident made it particularly horrifying, and the novelty of rail travel was tarnished in the public mind by this vivid addition it made to the list of ways one could depart this earth.

While Aldrich has plenty of stories about the different ways that passengers, railroad employees, and trespassers on railroad property were injured and killed, his emphasis is on the economics of railroad safety and how economic considerations played a vital role.  He points out that even after wood-and-strap-iron rails were replaced with all-metal rails and many other safety improvements were made, traveling by U. S. rail in 1907 was still 110 times as dangerous as flying in a modern (2006) airliner.  Still, 22 fatalities per billion passenger miles did not mean that you were taking your life in your hands every time you climbed onto a train.

From the railroad companies' point of view, safety was an expense, and like every other expense, they wanted it to pay a return on investment.  Railroads were virtually unregulated by the federal government until the establishment of the Interstate Commerce Commission (ICC) in 1887, and for many years the ICC restricted itself to setting freight rates for interstate commerce.  Some safety ideas, such as the "block signal" system of controlling train movements, rather than sending out paper orders and hoping everyone would synchronize their watches and keep to the schedule, not only reduced accidents but increased traffic flow, leading to greater utilization of existing plant and higher profits.  The railroads liked this kind of safety measure.

On the other hand, in 1922 the ICC ordered all carriers (rail lines) with revenues over $25 million to install automatic train control on at least one passenger line.  The idea of automatic train control, which dates back to the 1800s, is that instead of relying on the engine driver to see a visual block signal and stop the train, the automatic system would directly receive the signal's command and apply the brakes.  The rail companies reluctantly complied, and by 1930 had spent $26 million to install the system on over 15,000 miles of track. 

But as Aldrich shows, automatic train control made essentially no difference in the rail safety record, did not improve productivity, and cost a great deal of money.  During the Great Depression, many carriers asked for and received permission to cut back or remove automatic train control, and the ICC relented.  However, the same technology turned out to be useful for activating signals in the driver's cab (so-called "cab signals"), which have since become a standard safety feature of great help in fog or rain where visibility of the track-side signals is obscured. 

I was unaware of all this when I blogged a few years ago about a "cornfield meet" (head-on collision) between two freight trains in Texas that killed three employees and did millions of dollars of damage.  At the time, the railroads were installing something called Positive Train Control (PTC), which is nothing but an updated electronic form of automatic train control.  So the idea has been around for more than a century, it turns out, and is just now being implemented.  But as Aldrich points out, the accidents in which PTC would have made a difference are a small percentage of all mishaps.

While Aldrich makes a great case that economics was a huge factor in railroad safety, he gives less emphasis to something that continues to drive debates about all kinds of transportation safety today:  public perception.  He does point out that the average citizen has an exaggerated horror of types of death that are grisly and out of one's control, such as the snakehead accidents.  All the statistics in the world will not comfort the lizard part of one's brain that is primally terrified by the prospect of a fiery or gory death inside some machine that you cannot influence.  But other factors, such as speed and convenience, can overcome such fears.  For example, early automobile travel (say around 1920 to 1940) was demonstrably many times as dangerous as rail travel, yet the rail lines lost most of their short-range passenger business to the automobile in that period.  Ah, but the driver of a car has at least the illusion of control, thinking that while accidents may happen to other drivers, his superior skills will enable him to avoid a crash.  Well, maybe, but the statistics said otherwise.

As you would expect, engineers come in for starring roles in Aldrich's saga.  The technical press, including editors of such publications as Railway Age, brought constructive criticism to egregious safety problems and coordinated cooperation among carriers, government institutions, and private and university researchers to bring about notable improvements in safety systems, devices, and training.  This included issues such as the quality of bridge construction.  Early U. S. railroad bridges were built with the "link-and-pin" method, and the failure of even one joint in the structure would make the whole thing fall down, which it often did.  Complex failure modes in steel rails baffled engineers and scientists for decades until a concerted effort involving inventor Elmer Sperry's electrical track inspection system and advances in metallurgy discovered how to prevent them. 

An old friend of mine summed up the goal of engineering ethics with the two-word phrase, "No headlines."  While U. S. railroads are doing pretty well today by that measure, it is the end result of many decades of improvements and safety efforts.  And Mark Aldrich has given us that history in a rewarding and highly readable volume.

Sources:  Death Rode the Rails (Johns Hopkins Univ. Press, 2006), by Mark Aldrich, is the source for most of my material.  I also drew on the following website for additional details about "snakeheads":  https://aaronwmarrs.com/blog/2012/02/snakeheads-on-antebellum-railroads.html.  My blog about the head-on collision in Texas is at https://engineeringethicsblog.blogspot.com/2018/08/some-answers-about-panhandle-cornfield.html.

Monday, December 09, 2013

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.