In some cases they might add to the death toll of a crash.
Amtrak’s tragic derailment near Philadelphia last week has revived the question of whether or not trains should have seatbelts, just as cars do, with some public figures lobbying for them over social media:
But the New York Times settles the question pretty crisply in a story from Sunday: on trains, seatbelts often do more harm than good. Studies have found that lap seatbelts might increase spinal injuries, as a passenger’s neck gets thrust forward. Belts that go across both lap and shoulder would take care of that problem, but the stiffer seats required for this design might cause injuries to those who get tossed during a crash. Here’s the chief expert take:
“It’s been asked frequently, and honestly I remain uncertain, but the conclusion has always been that you can’t justify it,” said Steven R. Ditmeyer, a former director of research and research development at the Federal Railroad Administration.
The Times (and, earlier, Vox) drew many of these conclusions from a 2007 study of the potential safety benefits of using seatbelts on British passenger trains. This work evaluated six rail accidents that took place between 1996 and 2004 for the “structural intrusion” that occurred—basically, the open space on a train that gets filled with wreckage upon impact. When this intrusion is too great, it reduces the amount of “survival space” available to riders, and can lead to more fatalities as a result.
A couple numbers here make the case. In the six accidents during this period—all on trains without seatbelts—a total of 14 passengers (all from three of the crashes) died from structural intrusion. But an analysis found that if riders had been wearing seatbelts that locked them into place at the moment of impact, a potential 88 passengers might have been crushed. In other words, seatbelts could have made the death toll more than six times higher than it actually was.
From the report on how a lack of seatbelts actually helped these riders stay clear of a structural intrusion:
Passengers were seated in these areas prior to the impact, and it has therefore been concluded that passengers in this situation have been thrown or pushed clear during the incident, suffering some injury but surviving in the majority of cases.
The counterpoint is that passengers who aren’t wearing seatbelts might suffer injuries when they’re ejected from their seats. But the numbers suggest that’s less of a safety concern than structural intrusion. In the six rail crashes studied, 19 people were thrown from their seats, and eight of them survived.
The clear (if unfortunate) lesson from these crashes, in the words of the report, is that “no net safety benefit can be identified” from seatbelts:
Analysis suggests that restraining passengers in seats, whilst reducing the likelihood of ejection, may have other more serious consequences and create significant numbers of additional casualties (or fatalities) as a result of loss of survival space.
It’s hard to say whether this general conclusion about seatbelts and safety would have held true in the case of Amtrak Train 188. But the larger point is that the case for train seatbelts is unconvincing just based on safety alone—even without considering the high cost of implementing belts and the reduced comfort of train travel that would result. That lost comfort seems trivial in the face of lost lives, but over time it would likely result in more deaths, as people shifted from the relative safety of riding trains to the relative danger of driving cars.
The reason seatbelts have a greater benefit in cars, after all, is because the chance of a collision is much greater in the first place.