Not so fast

20mph zone along Wanstead Place20mph zone along Wanstead Place

With an increasing demand for 20mph speed limits on residential streets, Steve Wilks evaluates the impact of such limits and examines other solutions to improving road safety.

As chairman of the Safer Neighbourhoods Panel, one of my responsibilities is the safety of our suburban streets. One persistent problem is speeding. Certainly, when I have been out with the local PCSOs with speed cameras, a significant minority of vehicles exceed the speed limit – one car was caught doing 64mph in a 30mph road recently.

Some local residents have got together to adopt a policy of '20's plenty'. Speed, even at lower levels, is significant – a child hit at 30mph or 20mph can be the difference between life and death. 20's Plenty for Us is a not-for-profit organisation, and they campaign for 20mph to become the default limit on residential streets. Communities decide to change their driving behaviour.

However, in practice, these good intentions may have the opposite effect. In 2016 Bath and North East Somerset Council spent £871,000 bringing in 13 new 20mph zones. But one year on, the rate of people killed or seriously injured has gone up in seven of those zones. A spokesman said: "There is no simple explanation for this adverse trend, but it could be that local people perceive the area to be safer due to the presence of the 20mph restrictions and thus are less diligent when crossing roads, cycling or otherwise travelling." Paul Watters, head of public affairs at the AA, said: "By just whacking up signs everywhere you are not going to change things dramatically. However, previous studies have found that 20mph zones, in which traffic-calming measures are deployed in addition to speed limit signs, produce bigger reductions in drivers' average speeds." So, traffic calming measures might be a more effective way to reduce speeding. One of the most common is speed bumps. However, a significant disadvantage is that they may slow the response times of emergency vehicles.

In London in 1981, 274 pedestrians died in road accidents. By 2002, the annual toll had dropped to 107. This covers the main period of hump introduction in the London area. Even if we assume the entire benefit of 167 lives was due to speed bumps (and clearly there are other factors), the 500 lives lost annually in ambulances is three times greater. This means speed bumps may not be as effective in saving lives if we consider all vehicle users. Nevertheless, dynamic speed bumps – which only activate if a vehicle is travelling above a certain speed – are an (expensive) alternative and may improve the fatality statistics.

While we should aspire to roads free of obstruction wherever possible, it is worth compromising efficiency for safety if the measures are effective. To this end, the Wanstead Society has submitted a bid to Redbridge Council for new equipment to be installed locally.

Steve Wilks is a Conservative Party candidate for the Wanstead Village ward in the May 2018 local council elections. Follow him on Twitter @SteveWilks77

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