And Now: The 120 MPH Crash Test

Edward Niedermeyer
by Edward Niedermeyer

Usually it’s the Germans who we find continually pushing the crash-test envelope, but this time around the UK’s Fifth Gear TV Show that decided to crash a car at 120 MPH. Sure, the Germans already proved how much of a difference can be made by crashing at 50 MPH instead of the traditional 40 MPH, just as the Chinese can make any of their cars appear safe by testing at 35 MPH rather than 40 MPH. But 120 MPH? It’s never been done before…

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  • Dimwit Dimwit on Oct 21, 2011

    That was amazing. Does anyone know what the NCAP score was for that year/model?

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    • Redmondjp Redmondjp on Oct 21, 2011

      There is no amount of stars in the crash rating or enough airbags that would keep you alive in a crash like that! The sudden deceleration alone will kill you. Your aorta simply pops open (as it did on Princess Diana) and your blood pressure goes from 120 to zero about as fast as the car does. And your brain colliding with the inside of your skull makes sure that the job is finished! Car race crashes have proven this, with the likes of Dale Earnhardt and (just recently) Dan Wheldon, RIP.

  • M.S. Smith M.S. Smith on Oct 21, 2011

    I'm always amazed at how many people talk about how they "safely" hit 120 in their Honda Civic on car forums. It's everywhere except may the Toyota Corolla fansite. A stock vehicle simply is not meant to deal with this sort of speed. It doesn't matter when it was built. In fact, this rather reminds me of a kid I knew high school. He had a V8 Firebird, of the early 90s vintage I think, and went plowing down a road at 100+. He caught some air over a bump, lost control, and completely annihilated the car and himself. I remember going to the crash scene the next day, and there were still bits of the interior and broken CDs that had spilled across the grass as the car's frame came apart. He did survive, for which he was incredibly lucky, but spent many months in the hospital.

  • Chuckrs Chuckrs on Oct 21, 2011

    If you want to figure this out for yourself, get a good introductory physics or engineering text. Halliday and Resnick or Beer and Johnston both will work but there are plenty of others too. Look at the conservation of energy equation, but for figuring out the deceleration the impulse and momentum equation will tell you the average deceleration if you know duration of the crash. The trick for manufacturers is to get that actual deceleration curve as close to the flat line average as possible for as many accident scenarios as possible. All while making a car that people want to buy. Here's what the texts will tell you. 1) car into barrier at 60mph dissipates 1/4 the energy of car into barrier at 120mph - so does your body if you are in that car 2) roughly the same energy dissipation would occur in the highly unlikely case of two cars head on at either 60/60mph or 120/120mph. 3) no points for the deformation of the opposing car - symmetry considerations mean it doesn't matter 4) the small rebound that might occur means the total deceleration is greater than if the collision were perfectly inelastic - not by enough to matter in the slightest at 120mph - cars don't ricochet around like pool balls 5) no such thing as a perfectly balanced symmetric collision - a barrier won't give you what any actual collision will, but each actual collision will be slightly different anyway - that's why you try and set a reasonable, easy to replicate standard, like a barrier......

    • Redav Redav on Oct 24, 2011

      It's even simpler that that. The point of collision between two identical cars is a plane of symmetry. As such, no momentum can 'flow' over/through/across it. If there is no flow across this plane, then everything on the other side can be removed and simulated with a fixed barrier (immovable concrete wall). This is a basic technique for setting up free-body diagrams.

  • Robert Schwartz Robert Schwartz on Oct 21, 2011 Very Instructive.