Reduce Speed Now! (20’s plenty)

This article was published in 2007, in Newsletter 71.

20 mph zones: thin on the ground in Cambridge.
Image as described adjacent

In August last year a new Government circular Setting Local Speed Limits was published by the Department for Transport. This replaces one that was published as long ago as 1993. Since that date far more has become known about the effects of speed and especially excessive speed on crash rates. We as cyclists also know that speed of motor traffic is one of the major things that deter many cyclists, and potential cyclists, from making trips. Cambridgeshire County Council has in the past seemed reluctant to reduce speed limits, and has been especially slow in introducing 20 mph limits in residential areas.

Cambridge Cycling Campaign and other groups have asked for lower limits in their areas but have found this impossible due either to ‘the rules’ or the costs. In comparison, Hull has introduced over 100 areas with 20 mph limits. In these areas serious injuries have been reduced by 90% and child pedestrian casualties are down by 74%.

Although this has cost significant amounts of money it is estimated that for every pound spent it has saved ten in terms of injury costs. They started this programme in 1994 and it has been called ‘a beacon of good practice’.

Now the county council is conducting a ‘Review of Current Speed Limit Policy’. This has apparently already reached at least draft 2 and a workshop was held in February, but as far as we are aware campaign groups such as ourselves who have strong interests in the issue were not invited.

This issue will be raised at the Cambridge Area Joint Traffic Management Committee on 23 April, so there is now the opportunity to lobby Councillors. Final approval of a revised policy is expected from the County’s Cabinet in June or early July.

We’ve seen ‘draft 2’, and one change, which now follows the new government guidance-and which we very much welcome-is the change from the use of 85% speed to ‘average’ speed, when assessing if limits can be reduced without ‘hard’ measures (speed bumps to you). For example, previously to get a ‘self-enforcing’ 20 mph zone, at least 85% of vehicles were expected to be already travelling below 25 mph, whereas with the proposed new policy only some 50% need be travelling below 24 mph, a much less rigorous requirement. No doubt some FRS in statistics will question my use of ‘50%’ and ‘average’ in what is obviously a skew distribution, but traffic is not an exact science.

What concerns me is that, to gain all the benefits of reduced speeds, we need what might be called a ‘crash programme’ to get new limits introduced throughout Cambridgeshire. The Government guidance asks that limits are reviewed on all A and B roads and any necessary changes are implemented by 2011. I don’t think this will result in big changes to limits; some may even go up.

It is on urban residential streets, and (what should be) quiet rural roads where Government guidance ought to enable lower limits to be set over a wide area without major engineering measures. There seems little suggestion that extra funding will be available even for such simple measures, and my limited experience is that schemes proposed by, for example, parish councils will mostly fail, often because there is not the expertise to write them! Although some may claim that the introduction of individual 20 mph limits does not necessarily significantly reduce speeds, wider studies have shown that you do not have to reduce speeds by large amounts to reduce crashes significantly. The widespread introduction of such 20 mph limits also sends a clear message to drivers, and the results from areas such as Hull show that they are extremely effective in reducing road casualties, targets which Cambridgeshire is finding it hard to meet.

I was also surprised to find that the Officer leading this work within the County Council seemed unaware of the well-reported work done by Hull City Council, and only quotes just-started work in Portsmouth.


  • hit by a car at 40 mph, 9 out of 10 pedestrians will be killed
  • hit by a car at 30 mph, around 20% of pedestrians will be killed
  • hit by a car at 20 mph, only 2.5% of pedestrians will be killed


  • At 25 per cent above the average speed, a driver is about six times more likely to have an accident than a driver travelling at the average speed

Let us see if we can both reduce limits and make exceeding the limits on residential roads and quiet lanes as anti-social as drink driving (and using a hand held mobile?)

Jim Chisholm