The 20mph zone has led to a “statistically significant” reduction in the speeds that vehicles travel through the village, an analysis of the scheme has found.
Cambridgeshire County Council introduced the limit through Histon and Impington in February 2024, and the first year evaluation has found that average speeds on the main routes fell by 14%, from 26.2 to 22.4mph.
A report presented to the Highways and Transport Committee explained the reduction was “statistically significant”, meaning there is “strong evidence of a material change rather than fluctuation or chance”.
The analysis also found an early indication that the number of collisions in the village may have decreased. There was an average of 4.4 collisions a year in the seven years before the 20mph limit, compared with just one reported collision in the period since it was introduced – a potential reduction of 77%.
Analysis
Histon and Impington’s results were among eight 20mph zones that were analysed and presented to councillors at the County Council’s Highways and Transport Committee last Tuesday (1 September).
All had recorded reductions in average speeds, with the largest falls seen in areas where speeds had been highest before the limit was introduced. The analysis used Compass speed data collected from vehicles travelling on the road network from March 2023 onwards.
While H&I Councillor Ros Hathorn says the initial signs are encouraging, additional years of data will be required “to substantiate the findings”.
Speaking at the meeting, Ros said: “[The 20mph zone] hasn’t changed speeds by 10mph, but it has significantly reduced speeds and every reduction means that accidents are less likely to happen and the consequences less likely to be severe.”
She also stressed there is a “big qualitative element” to having a 20mph zone. For example, she explained it communicates to drivers that they are entering a village where they could be sharing roads with the community. “It also gives parents and those with reduced mobility in the village greater confidence,” she said.
Ros added: “I’ve also had a grandparent take me to one side and tell me about how their grandchild was involved in a terrible accident and lost a leg. I’ve heard many personal stories – and a lot of people are really really pleased to see this measure being implemented.”
Eighteen more 20mph zones are being proposed across Cambridge – including at Hills Road and Mitcham’s Corner – and the County Council received over 1,000 responses during its statutory consultation over the summer. Meanwhile, a 20mph zone will be introduced at Orchard Park this autumn.
Compliance
Although vehicle speeds have fallen in Histon and Impington, the analysis also showed that many drivers are still travelling above the 20mph limit.
Before the zone was introduced, 85% of vehicles were travelling below 31.4mph. Afterwards, this figure had fallen to 28.5mph – showing a reduction in the speed at which the majority of vehicles were travelling, but not necessarily that they were complying with the new limit.
On the B1049 at Cottenham Road, between The Green and the northern edge of the village, the data showed that average southbound speeds fell from 32.3mph to 29.3mph.
Cllr Ian Gardener, who represents Alconbury and Kimbolton, asked whether “any further measures to improve compliance” were being considered.
Jeremy Smith, the County Council’s Head of Sustainable Transport and Strategy, who presented the report, said the ultimate aim was to reduce collisions rather than “blindly seeking compliance with the speed limits”.
“However, compliance with the speed limit is obviously a fairly big issue to many parts of the population,” he added.
There are now 25 roads across Cambridgeshire with 20mph zones.
The H&I scheme cost around £24,000 and covers almost the entirety of the village – which Ros argues is good value for money, pointing out that a set of speed cushions alone can cost around £25,000 as part of a traffic-calming scheme.
She added: “I would like to thank Tom McKeown and Histon and Impington Parish Council for the work they did in winning support and funding for the scheme.”
Speedwatch is always keen to get more volunteers. Email Ros at ros.hathorn@cambridgeshire.gov.uk if you’d consider getting involved.
Additional reporting by Eoin McCaul from the Local Democracy Reporting Service.
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