In the antiseptic present, many crash tests happen nowhere in particular. The smashing and crumpling goes down inside computers and on screens, because virtual exams are cheaper and usually just as effective as ones that rattle crash dummies.
That's fine in most case, but not when you're trying to prove you can make train crashes less deadly. "Computer models, at the moment, do not perfectly describe deformation,” says Michael Zimmermann. He's an engineer with the German Aerospace Center, or DLR, the country's NASA equivalent, which is working on a new kind of passenger rail design. (Yes, ze Germans are into trains like the Americans are into the Moon.)
A screen just wouldn't do, so earlier this month, gleeful German engineers took a new passenger rail design for a satisfying smash.
The Germans' fun with wheels and steel is centered on a new kind of crumple zone. Ubiquitous in cars, crumple zones are designed to buckle and absorb the kinetic energy produced by a crash, thus protecting the bodies in the passenger compartment. In rail cars, engineers build these compartments into the front and caboose.
Thanks to the switches and tracks that keep trains away from each other, rail crashes are rare. But accidents happen, and they can be deadly. In the worst case scenario, colliding rail cars “telescope,” squishing inside each other like the segments of a spyglass. Designing safe rail cars is the way to avoid that kind of horror show, says Allan Zarembski, a railway engineer with the University of Delaware. "It’s the last way of saving somebody in a car."
In 2008, a Metrolink commuter train and a freight train collided in Los Angeles, killing 25 and seriously injuring more than 100. Authorities say better design (among other adjustments) would have helped: Metrolink has since spent more than $250 million on trains with crumple zones.
The Germans' new design has added a metallic sparkle to the crumple zone. Along with the simple implode-able space, the new car body concept includes a series of tapered metal tubes. If the car gets into a jam, these tubes are forced into increasingly tiny slots. This "controlled deformation process" absorbs most of the kinetic energy produced by the crash. That’s in place of, say, your body.
For the test, at a facility in Görlitz, near the Polish border, the engineers fit their totally tubular prototype onto an 80-ton cargo tanker carriage. They dotted the structure with sensors to take constant measurements, and set up high-speed cameras to record the crash from different angles. They sat the prototype on the track and sent another cargo tanker its way at 11.5 mph. Okay, so not the fastest, but still: pow.
The new design pretty much worked. The tubes pushed into their slots, the rail car wasn’t seriously damaged, and the prototype slid backward just a bit.
This test cost less than $100,000, but there's more work to do. The German engineers need to analyze the data and plug it back into computer simulations. They’ll work to match the setup with lightweight materials, to keep emissions down. And they’ll evaluate if the concept can work for a whole train, not just one car. Because while smashing steel is fun, it’s not something Germans want to encounter on their commutes.
