Philip Hammond, MP - Please Help With My Physics Homework
Picture the scene - you’re driving along the motorway at 70 mph when as you crest a hill, you suddenly notice a constellation of red brake lights ahead. There’s been some sort of incident, and the traffic has come to a complete stop.
You stand on the brakes and do everything you can to stop your car. Thankfully, you’d judged the distance to the car you were behind perfectly (21m) , and you manage to stop a few millimetres prior to an actual collision.
Now imagine the same scene, but instead of driving at 70 mph, you’re doing 80 mph, and you’re the same distance from the car ahead of you. How fast do you think you’ll be doing with the inevitable collision comes?
If you go to the Highway Code’s web site, Rule 126 has handy chart that’ll show you how overall stopping distance is related to speed:
The trouble is, this doesn’t go up to 80 mph - the government’s new economy-boosting proposed speed limit. So I’ve added this to the chart (click to enlarge):
What this shows is that the difference in total stopping distances between 70 mph (96 metres), and 80 mph (121 metres) is slightly greater than just the braking distance at 40 mph (24m).
In other words, at the point on the road at which you would have stopped from 70 mph, you’ll still be travelling at a shade over 40 mph.
So here’s a challenge to our marvellous Minister for [Motorised] Transport: I’ve only worked these numbers out using the laws of physics, and they might be wrong. So please can you test them out for yourself. Get in the car, drive at 80mph, and do be sure to let us all know if that 40mph impact knocks some sense into you.
In the meantime, here’s some TV to watch:
And some more here from our favourite impartial TV journalists:
So Karl next time you are thrashing that hummer of yours down the A1 at 120mph you’ll be blaming hammond?
No. I’ll get my barrister to blame him as part of a brilliant defence that’ll allow me to keep my license again.
Well, if everyone’s already doing 80 in a 70 zone, perhaps a more accurate, and dramatic, comparison would be 90 to 80?
I’m very concerned that you imply its OK to keep a 21m gap at 70mph, as this is only the thinking distance before an alert driver will even touch the brake pedal. If the driver in front is less alert, or hits an obstacle in poor visibility, you have no chance with a 21m gap. It is extremely unwise to count on the driver in front to see and think for you!
@Don - we’re dealing with a theoretical minimum, rather than what’s actually safe in practice. That said, look at how many people drive closer than 21m at 70mph!
Being able to travel 10mph faster towards cities is a great way to really put pressure on the bottle necks into the cities and the city streets and junctions themselves causing not faster moving, more efficient economy boosting traffic, but more congestion. The idea that car speeds are being pandered to also sends out the message that car use is a good idea, encouraging more people to travel by car. It’s a lose, lose situation. It will however burn a lot more fuel, giving the government a massive increase in tax earned on fuel to play with to bail banks out etc.
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Of course it’s important to be reminded that under adverse conditions [hinted at in the HC] braking distances in the wet can be doubled and up to ten times or more for snowy / icy conditions, but YMMV
In some circumstances water + diesel, or in the case of insufficient tread depth and deep water, all bets are off.
YMMV= Your mileage may vary.
I remember being told to keep 100m distance when I learned to drive (in Germany Autobahns have big black and white markers at 50m intervals so it’s easy to do. Of course when you do this someone in a Mercedes drives into the gap and you’ve suddenly got a 30m gap in front, so you back off to allow a bit more space, and then along comes Audi Man on his own private Grand Prix and fills the gap again, except that this time he’s being followed by Captain Golf who squeezes behind so close I can read the dealers name on his licence plate.
And people say cycling is dangerous.
We have twelve deaths a day on the roads in Germany, on a good day. That’s not accidents, that’s people killed.
So I take the train or ride a bike: Driving is way too dangerous.
Which basically goes to show that the car, if not ruled down, everytime, will kill and its occupants..thsnkyouveryfkgmuch Mr Hammond for allowing more people to die, no - thank you AGAIN, much appreciated!!!