By Johnny Sharp

The path towards reducing the number of people killed or seriously injured on UK roads is a long and ongoing one, and in pursuit of increased progress on that journey, last November CIHT published a report outlining the challenges and five key areas of focus. 

One of the experts involved was Kate Carpenter, and she feels that she and fellow contributors were on their own learning curve about where to focus effort surrounding safety concerns. 

“While all five elements matter, highway authorities really only have control over some things,” Carpenter explains. “And the thing we’ve found that they can control most effectively over the largest area in a short time at modest cost is speed.

“We found the London 20mph zones very much mirror the experience in Wales – a disproportionate benefit in the reduction in the number and severity of collisions, in return for a relatively low cost compared to what we conventionally spend on highways. 

“It is counterintuitive – we have known about relationships between speed and safety outcomes for decades, but were surprised to find that small differences can make such a big and sustained improvement. So, CIHT guidance reflected the results of that work. We recognise that different highways, different authorities and different classifications of highways have different constraints and priorities.”

Improving the road experience for all

The move towards 20mph speed limits hasn’t been without resistance, as many will have noticed, but as other regions of the UK look set to adopt such practices, Carpenter points out that it will have an effect on other areas, whether that’s safer roads and safer road users, or post-collision responses. 

Research has consistently found that lower speeds help improve traffic flow, making life easier for everyone from emergency services through to vulnerable road users, while also offering benefits for a group that sometimes claim they’re being victimised: motorists who are keen to get from A to B as efficiently as possible, not to mention more economically. 

“People naturally think lower speed limits means slower journeys,” says Carpenter, “but actually, it’s counterintuitive, as by travelling at a lower speed traffic is smoother, so you may get there quicker; measured journey times are generally only slightly longer, but were more consistent, which drivers rate as very important. Lower speed and smoother throughput mean less acceleration and braking, which are the things that dominate total fuel use.

“Some people say cars are less fuel-efficient at a constant 20mph, which is true, but nobody drives at a constant 30mph in a 30mph limit area – in fact the mean speed will be more like 17-18 miles an hour if you’re lucky.

“So, with 20mph limits, you end up with less variance, and that means more reliable journeys with less braking and acceleration – therefore less fuel use, and lower cost – plus less congestion, lower carbon emissions and cleaner air from the local population point of view, and fewer collisions. Insurers have found this means premiums are lower compared to an identical case over the border.”

Carpenter feels that a key factor in spreading safety concerns is taking the public along – something that has not always been done effectively.

“If we can make the benefits of driving at lower speeds clearer, that will be much more effective than saying: ‘You’re a terrible person, a bad driver and you’ll get points on your licence.’ 

“The way we talk about things needs to be calmer, more respectful and more balanced, as nobody benefits from a slanging match. It doesn’t help to suggest that drivers or pedestrians are stupid, lazy or neglectful, which is the kind of messaging we see sometimes. All people make mistakes, and should not be harmed as a result.

“We aim to give helpful guidance for highway authorities to talk to the public constructively, promoting safe road use in the widest context of what does the public good.”