Neil Turner's Blog

Blogging about technology and randomness since 2002

Too fast

Burnt out car

(This is the second time this week that I’ll be posting two blog entries on the same day – you lucky people.)

Later this year, the Department for Transport is to launch a consultation on increasing the maximum speed limit on motorways in England and Wales to 80mph. Right now, it’s 70 mph unless otherwise stated.

The reasons give for the change are:

  1. Advances in car safety systems and brakes mean that there isn’t likely to be a big increase in accidents
  2. As many as 49% of drivers go faster than 70mph anyway
  3. A number other EU countries like France have speed limits of 130km/h, which is 80.7mph

Unfortunately, I can’t agree to this, and here’s why:

  1. Any increase in speed limit will increase accidents. Whilst cars and roads are safer, the braking distance at 80mph is still longer than at 70mph. I’m not an expert, but I would expect an increase in minor accidents if limit is changed, which will cause congestion problems.
  2. At 80mph your car will burn 20% more fuel than at 70mph. This will increase carbon emissions, at a time when the government is keen to cut them, and also burn through our finite fossil fuel reserves more quickly. In fifth gear, you car is most efficient when cruising at 55mph – and most cars do not have six-speed gearboxes. (For more, see this article on fuel efficient driving – you may save £100s a year)
  3. At present, you tend not to be caught speeding unless you exceed the speed limit by 10% plus 2mph. Theoretically this means you can currently get away with driving at 79mph; however, if the speed limit is increased to 80mph, this may mean that you could drive at 90mph without being convicted. And that could lead to further accidents, as per my first point.
  4. It could increase congestion. On sections of the M42, M25, and, from 2013, the M62, there are variable speed limits, as reducing the speed limit during busy periods keeps cars moving. Increasing the speed limit on busy motorways could encourage more ‘stop-start’ motoring, leading to queues and congestion. In particular, it won’t ease congestion caused by overtaking lorries and coaches, which will still probably be limited to 56 or 62mph.
  5. Just because the law is regularly flouted, doesn’t mean that it should be changed. If 49% of drivers are breaking the law, then maybe that’s to do with poor enforcement rather than the law being wrong.
  6. This would only effect England and Wales, and not Scotland. If enacted, then there’s the potential for a huge increase in speeding convictions in Scotland if people forget when they cross the border (although all Scottish motorways display ’70’ signs rather than the black and white national speed limit sign, since there is no defined speed limit for motorways in Scotland.)

The consultation hasn’t started yet, but I’ll be feeding in my views.

One Comment

  1. I’m afraid I couldn’t disagree more, the speed limits on the continent are vastly higher than here and they have less accidents, it’s down to driver education and awareness, not how fast you travel.

    Braking distances vary by vehicle taking into account many factors, including speed, road surface, weather conditions, weight, size, drive reaction. Increasing one of these would not adversely affect breaking distances to the point of increasing accidents.