Warning triangles, sign removal, and casualty extraction: letters from the public and innovation stories from road safety

Dr Shaun Helman reviews random letters from the public which illustrate the different perspectives on topics and what this can teach us as road safety researchers.

Published on 29 April 2024

Share this article:

Working at TRL, I’ve been lucky enough to receive letters and emails from members of the public who are interested in road safety and other aspects of the transport system. Early in my time at the company I did not always enjoy such correspondence; while the people writing were sometimes asking open minded questions, sometimes an opinionated member of the public was simply writing to tell us all the things they thought we had gotten wrong.

Usually though such letters are well intentioned, and even if they don’t always reflect the state-of-the-art in terms of knowledge (“Thank you for your letter suggesting the fitting of spikes to steering wheels to encourage drivers to slow down, but we have intelligent speed assistance now, which has the benefit of reducing rather than increasing road casualties…”) they usually ask genuine questions.

A recent letter got me thinking and inspired me to write this article. It was about warning triangles - the sorts we sometimes have in our cars so that we can place them on the road to warn approaching traffic if we break down. The writer asked if TRL could invent a warning triangle that rather than being placed in the road could be fitted to the roof of a stranded vehicle. By being placed on the roof of the car, the writer reasoned, power from the vehicle could illuminate the triangle making it more visible, something its height in the scene would also provide.

In researching the topic to inform my reply, I realised there is less evidence on the effectiveness of warning triangles than one might think. While there is an acceptance that advanced warning of breakdowns and other hazards on the road ahead is a good thing (it is one of the often-cited advantages of connected vehicles) I was not able to find direct evidence that the use of warning triangles placed on the road has a net benefit. There are even reasons to think that asking drivers stay near live traffic for longer than they otherwise would - to place the triangle - may outweigh any visibility benefits. Colleagues have also pointed out that such devices can easily be displaced by the wind caused by passing traffic, leading to potential conflicts. Rule 276 of the Highway Code seems at least partly informed by such thinking, in that it states that these triangles should never be used on motorways. This paper seems to take a technology-based approach to the issue, by designing a remote warning triangle device that can self-deploy.

What if this letter, from a concerned member of the public, has cut through all of the complexity and settled on a simple solution? I don’t know. My reply noted that the idea seemed sensible, and that it might be something we could test as part of a systemwide approach to minimising risk in such situations.

What I didn’t write in my reply, as it seemed rather tangential, is how philosophical the question made me feel. It was such a great example of what has been called ‘outside the box thinking' but which is really just 'challenging the way we have always done things'. There is a track record in science, and in road safety, of such questions leading to genuine improvements. The obvious examples from broader science and medicine are Ignaz Semmelweis’s observations of death rates on maternity wards leading to handwashing practices, and evidence-based medicine discovering (albeit later than we would have liked) that advice available in medical textbooks from the early 1940s to the late 1980s on baby sleeping positions was wrong; it led to greater chances of infant death, not lesser.

There are two fantastic examples in road safety that also come to mind.

First, there is the TRL work on road signage used at temporary roadworks. At a time when signs warning oncoming drivers about temporary roadworks were being placed both on the nearside and offside approach, people were rightly trying to find ways to make crossing high speed roads while carrying enormous metal signs safer. At some point, someone thought to ask the question “do road workers need to cross the road at all?” A programme of research demonstrated that the offside signs could be entirely removed with no meaningful impact on the behaviour of drivers approaching the closure, saving millions of high risk events from having to occur, and saving lives in the process.

Another example is one of the most impressive applications of ‘outside the box thinking’ that I’ve seen in road safety or anywhere. Tim Nutbeam and his collaborators have challenged the traditional approach to the extrication of road collision casualties from crashed vehicles. In work funded by the Road Safety Trust, a number of published articles and reports such as this one have shown that traditional practice - which prioritises the minimisation of spinal movement and often results in large delays before extrication can occur - can be improved. Allowing road collision casualties to extract themselves from crashed vehicles instead (when they are able) reduces harm and even shows lower levels of spinal movement than the traditional approach. People have told me that the old approach to extrication was so ingrained in operational practice that they knew of cases in which casualties had been extracted from the police vehicle into which they had put themselves after a collision; cutting equipment would even be used to remove the roof of the police vehicle, as per protocol. To challenge something this akin to dogma takes a commitment to the scientific method that I hope I possess myself, but I fear I may not.

In light of examples such as these, I have come to hold the opinion that the sensible questioning of ‘the way we’ve always done things’ is to be encouraged. For every few hundred “why don’t we have spikes in the middle of steering wheels” there is probably a “do road workers need to cross the road at all” or a “is delayed extrication the best approach”. Even at this ratio, we might learn something new and improve outcomes enough to make the process worthwhile.

I have since received a second letter from the person who initially wrote to me about warning triangles, thanking me for taking the time to reply to the first. I would like to thank them for writing me the first letter as it has enabled me to reflect on the things I’ve written about in this article, and has reminded me that none of us has all the right answers. Indeed very often we are not even asking the right questions.

Get in Touch

Have a question? Speak to one of our experts today