Thursday, May 7, 2009

Timeline of a vehicle crash.

      Here is an interesting write up about safety features in Ford's Falcon - http://www.drive.com.au/Editorial/ArticleDetail.aspx?ArticleID=56781&vf=26

Here is a video of the 50km/hr crash test - http://media.drive.com.au/?rid=40239

      The most interesting information is towards the end of the write up where they have given the timeline of the collision. The important part is at the end of that timeline - '150-300 ms - Occupant becomes aware of collision.' Thus, it can take up to one third of a second for us to just to become aware of the situation completely. Acting upon it will take at least another 200-300ms (brain will process the inputs, inject epinephrine into the nervous system, and will send signals to the heart and various muscles; after receiving the signals the muscles will begin their work). Completing the act (taking a solid hold of the handle/steering wheel, zeroing the throttle, depressing the brakes completely) will take at least another 500ms. The total comes to around 1100 ms which is a very optimistic estimate. Generally, 1.5 secs is the figure used. With rain or darkness the figure may double. It will take some more time for the vehicle to actually start braking after the brakes are pressed. Assuming that this whole episode takes an optimistic 1.5 secs, the car/bike (at 50 km/hr) will have travelled around 20 meters even before it starts to slow down! Age, vision acuteness and the surprise factor ('that puppy came out of nowhere!') are other important things to be considered.
      The reaction time can be decreased by driving practice, but only by a small amount. The only thing which can improve the situation is to have urgent & reliable brakes. The significance of good brakes can hardly be overstated. Losing a mere one tenth of second to your non-urgent(a better word welcome :)) means travelling four more feet without braking. I hope that my school pal, with whom I argue many times over the sloppy brakes on his bike reads this post.

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