German mdr Regional TV has done a rather spectacular set of crash tests (Video with german narration, but the video speaks for itself). They were running a test of a 10t truck vs. a set of 2.4t concrete truck barriers, at 50 kph collision speed.
As expected, the truck goes trough the barrier almost without any speed loss in a frontal collision. That is mostly, because the barriers are unanchored, so they are sent spinning. The truck loses both frontal wheels, though, and is consequently harried.
A second test with a 45 deg collision goes spectacularly wrong: The truck is inflected into the barrier, and goes through the barrier at a right angle again, instead of being deflected and guided following the barrier.
Further investigation reveals that a truck has of course an extremely sturdy, rectangular frame on which the entire chassis and the load rest. The frame is being caught by the barrier and acts as a hook, drawing the load into the barrier instead of being guided by it.
The video is interesting on multiple levels:
- It shows how much more energy there is in a moving, loaded truck compared to a personal vehicle at the same speed. Where personal vehicles and motorbikes are being pulverised by a 2.4t barrier, the truck at 4 times the weight of the barrier simply moves the barrier away and sends it skidding and spinning.
- That is not just true in a terrorist attack. The same energy is in play every time you are moving in traffic next to a truck or bus. And you car is about half the weight of such a concrete barrier, unless you are sitting in a SUV. Bicycles do not even register (Article in German).
- It shows that a proper barrier needs to be solidly anchored to the ground in order to be able to take the energy out of the moving truck. Friction alone is not going to help. That’s expensive and horrendously complicated in terms of event logistics.
- The tone of the entire report is needlessly alarmist. Of course an unanchored sliding barrier is insufficient, and that has been demonstrated pretty impressively. But that’s fixable in more than one possible way, and needs to be done. Still no need to panic.
So, trucks. Keep an eye on them in traffic, all the time. Because mass matters.