Should there be a limit to our faith in limits?

By Dr Helen Wells

Proposals announced by the government today suggest that drivers caught driving at twice the speed limit could receive an automatic driving ban. There are also, however, discussions about whether or not ‘minor speeders’ caught just over the speed limit should receive less points than they do currently – two points instead of three. In the same consultation, the government is also keen to explore the idea that formal ‘drug-drive’ limits should be established to try to help curb the increasing numbers of people killed or seriously injured in crashes where drugs were felt to be a contributing factor.

As expected, the usual pressure and interest groups have spoken out in favour of, or against the proposals, rehearsing the usual arguments about unfairly taxing respectable drivers or, on the other hand, accusing the government of trivialising smaller infringements of the limit.

What strikes me about these proposals, and suggestions that we could soon see ‘drugs breathalysers’ to make prosecutions for drug driving easier, is that they continue to place a great deal of faith in the notion of 'the limit' – as though it had some inherent quality that meant it represented an accurate assessment of the relative levels of danger caused in any particular driving situation.

This faith is demonstrated by campaigns like ‘it’s 30 for a reason’ and the dramatic TV advert where a little girl gets killed by a car travelling at 35mph and then ‘only’ very seriously injured by a car travelling at the 30mph . One wonders if it would not be better to advise motorists that, in such situations, they should drive at whatever speed means that they would not hit the child in the first place – not that 30 is some magic number that, if we all stick to it, means we are inevitably driving ‘safely’. The advert would seem to suggest that 30mph was, in fact, too fast in the circumstances, and that ‘the reason’ ‘it’ is ‘30’ is that it’s technically and administratively far more convenient than if we operated some contextualised, ‘common sense’ interpretation of risky driving practices.

The idea that 29mph is unquestionably safe, while 31mph is inevitably dangerous surely seems somewhat oversimplistic to any driver who has driven past a school gate at 3.15 pm and past the same gate again at 3.15 am.

But the limit is a crucial aspect of the use of ‘techno-fixes’ like the speed camera, and also the any kind of ‘drug-ometer’ as has been suggested today. The speed camera relies upon complex situations being converted into simple dichotomies of safe/unsafe behaviour in order to be able to function and therein, I think, lies the source of a lot of drivers problems with them.

Similarly, a drug-ometer, like an alcohol breathalyser will, presumably, have to operate on some notion of ‘safe’ and ‘dangerous’ levels of drugs, and to do so it will have to ignore issues such as the age, weight, build, health, and previous exposure/using history of the person being tested. Inevitably, as with drink-driving, some people under ‘the limit’ will be a danger to themselves and others while, theoretically, some people over ‘the limit’ could be driving safely. Hence the calls that resurface periodically for a zero-limit for alcohol while driving – a limit that many people chose to self-impose for the very reason that they know that they react differently at different times to different amounts of alcohol.

The Association of Chief Police Officers Head of Roads Policing once suggested to me that the ideal Police tool for tackling road safety problems was an ‘impairmentometer’. This tool, he enthused, would be able to measure not just alcohol, but drug levels, tiredness, eyesight problems, and seemingly limitless (excuse the pun) other potential causes of road crashes.

While such techno-fixes and gadgets are no doubt appealing on ‘efficiency’ and ‘economy’ grounds, being more reliable and cheaper than a human tasked with doing the same job, I would query how we judge their ‘effectiveness’. In reconceptualising the problem to render it ‘techno-fixable’, as we seem to do every time we enforce a limit out of context, are we actually still tackling the problem we set out to tackle? We could wait to find out whether we cut road deaths – or not. Or we could be a bit more canny in designing our interventions to make sure that the tools we have for dealing with the problems on our roads don’t neglect reality for the sake of simplicity.

You can read more about techno-fixing road safety problems here.