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Debate about effectiveness of Cambridge 20mph zones

Only small changes being reported following first wave of changes

Critics are questioning the impact of a city council scheme to introduce 20mph speed limits on the majority of Cambridge’s residential and shopping streets. So far 58 streets in the north of the city have seen their speed limit reduced from 30mph to 20mph and the majority have seen a change of less than 1mph – average speeds on most of the streets already being below 20mph even before the changes.

The project is due to be rolled out across the city, but some are questioning the value of what will be a £600,000 investment with the biggest change seen on any road thus far less than 3mph.

Local Conservative activist Andy Bower, told Cambridge News that he felt there were other, more important issues for cyclists that were being overlooked.

“I think it’s fine that residents are being consulted, but I feel councillors have pushed the whole process without considering the facts, what the practical impact is going to be.

“The police have expressed their view time and time again that it doesn’t seem to be worthwhile. Perhaps councillors should pay attention to that advice. If you’re cycling down Mill Road the threat isn’t how fast you’re going – the real threat is people coming out of side streets without looking.”

However, it is often argued that even small reductions in driving speed can have a real benefit in safety terms. Results show that the largest speed reductions in Cambridge have been on the streets that had the highest averages.

Andy Preston, the city council’s project delivery and environment manager, said:

“Of those streets where average traffic speeds were previously above 20mph, some 93 per cent have seen a reduction. Only three of these streets have seen an increase in average speeds, but by a marginal degree...and the resultant mean traffic speeds remain relatively low.

“All streets that were surveyed in the north area now have average speeds of 24mph or less, with 56 per cent having average speeds of 20mph or less.”

Al Storer, from the Cambridge Cycling Campaign, said that the group supported the continued roll-out of the 20mph scheme, arguing that a consistent limit in residential and retail streets would help with compliance as drivers would be in less doubt about what the limit is. However, he argued that the changes would prove more effective if police showed greater support.

"The preliminary results from north area do only show small drops, however the data shows that in many streets the average was already well below 20mph so we would not expect much reduction there. It appears the largest reductions have been on the streets that had the highest averages.

"Better compliance may be achieved if the police would take enforcement of the limit seriously. Despite local residents asking for it as a priority the local policing team have taken little interest in doing so, which the regular speeders no doubt know.  We are sceptical that a 20mph limit on major through streets can be effective without enforcement and/or measures to reduce speeds and reduce through traffic."

Last year, government ministers and members of the All Party Parliamentary Cycling Group reacted with astonishment when a senior police officer representing the Association of Chief Police Officers (ACPO) at the Get Britain Cycling parliamentary inquiry said the body’s guidance was for such speed limits not to be enforced. In a statement, ACPO later clarified that “it is for local police forces to apply a proportionate approach to enforcement of 20mph limits based on risk to individuals, property and the seriousness of any breach.”

A spokesman from Cambridgeshire Constabulary said: “We are supportive of any scheme that will improve road safety and we have been active members of the multi-agency implementation group throughout this process.”

In any case, the merits of 20mph zones should perhaps not be measured purely in terms of the impact on drivers. One of Cambridge City Council’s stated aims in imposing 20mph speed limits is to provide road conditions that encourage active and sustainable modes of travel, such as walking and cycling.

Following a trial last year, Edinburgh looks set to introduce 20mph zones across the city with one of the main benefits found to have been that people felt safer. During the trial, cycling and walking journeys rose by 5 per cent and 7 per cent respectively, while car trips fell by 3 per cent. The percentage of children riding a bike to school rose from 4 per cent to 12 per cent, and from 3 per cent to 21 per cent among older primary age pupils. Furthermore, the proportion of parents willing to let their children play outside more than doubled from 31 per cent to 66 per cent.

Consultation packs for the next part of the Cambridge project will now be sent out. More information is available at

Alex has written for more cricket publications than the rest of the team combined. Despite the apparent evidence of this picture, he doesn't especially like cake.

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