Authors: Victoria Pyta, Neale Kinnear, Alistair Cooper, Shaun Helman

When Covid-19 hit the Isle of Man in March 2020, they responded by implementing a national speed limit of 40 miles per hour to derestricted roads and ones which normally have 60mph and 50mph limits. Which might lead you to ask… but what has speed got to do with it?

The Isle of Man was very clear in their media release that the move was “designed to minimise the risk of accidents leading to bed spaces being occupied as the Island’s health service plans for a spike in the number of people needing hospital treatment”. This action was one of the recommendations made in a blog by public health experts in the British Medical Journal. And the response, on social media at least, has generally been supportive.

With a small population and a single hospital, the island’s Government seems to have effectively tapped into the local community’s desire to support their health service at a time when they are acutely aware of its limits and the personal impacts on health workers. And, there are initial signs that (combined with lower traffic volumes), the new speed limit may be having the desired effect.

Whilst it is too early to draw conclusions, a reduction in casualties is in line with experience in other locations where speed limits have been reduced. For example, the city-wide reduction in the speed limit from 30 to 20 mph in Bristol in 2008, which achieved a 63% reduction in fatalities on the city’s roads over a nine year period.

Elsewhere in Britain, however, there has been a run of stories in the media reporting cases of drivers being caught at extreme speeds and Police concerns that drivers think the lockdown is an excuse for taking unnecessary risks and treating empty roads “like race tracks”. But are they?

Evidence from previous studies shows that the majority (52%) of drivers are speed limit compliant while a third of drivers break the speed limit occasionally[1]. However, one in seven drivers on Britain’s roads are classified as ‘excessive speeders’. Excessive speeders are drivers who regularly drive above 35, 40 or even 50 mph in a 30 mph limit, report driving at 80 in 60 mph limits and 90 in 70 mph limits. Drivers in this group are characterised by speeding for opportunistic reasons (like the roads being empty) and reactive reasons (when feeling stressed or angry). Unsurprisingly these drivers are also more likely to be involved in collisions where they are deemed at fault. When asked what stops them driving any faster, excessive speeders are less likely to report feelings of safety or risk, as more compliant drivers do, and are instead simply motivated by avoiding detection by the police.

Unfortunately, it looks like some people are engaging in some particularly dangerous driving behaviour, putting themselves and key workers on the roads at risk in doing so. However, creating an impression that many people are taking advantage of the quieter roads and speeding may risk contributing to a misperception of the social norm in the majority of drivers, and that could encourage some people to take more risks with their speed.

Additionally, some are perpetuating the belief that “low-level” speeding is not really a problem and should not be a priority at this time. For example, The Times reported that some motorists have received letters from police forces saying it is “not in the public interest” at this time to pursue prosecutions for “lower-level driving offences”. In reality, a majority of motorists comply with speed limits, and the majority of people who speed are “only a little bit over”.

There are always examples of extreme behaviour that can be quoted, but when the whole distribution of vehicle speeds on the network moves up by a couple of miles per hour, there is a large impact on the number of serious injuries and fatalities. As a rule of thumb, a 1% increase in average speed is associated with a 3% increase in serious injury crashes and a 4% increase in fatal crashes[2]. The impact of small increases in speeds on pedestrians and cyclists who don’t have the protection afforded by a vehicle is even worse. The graph below shows a sharp rise in the risk of a pedestrian fatality for impact speeds from 30 miles per hour. Serious injuries (resulting in a person needing medical treatment and potentially being admitted to hospital) start to rise at impact speeds well below 30 miles per hour.

Compliance with speed limits is influenced by attitudes and perceptions of social norms, and also by the perceptions of enforcement[3]. These are affected by the way that Police and the media portray speeding behaviours and their severity. There is currently a risk of reinforcing inaccurate beliefs and norms by over-emphasizing infrequent but severe examples, while downplaying the seriousness of much more frequent (and more socially accepted) “low-level” speeding.  

Additional trauma from speeding and other dangerous activities diminishes our health service’s capacity to cope in the current crisis. Therefore, police should maintain visible and steady levels of speeding enforcement as much as possible. Giving the message that low‑level speeding doesn’t matter may have undesirable consequences. At this unprecedented time, we should take heed of the proactive actions on the Isle of Man and be doing everything we can to support the government’s messaging of protecting the NHS.

TRL is analysing data on the impact of reduced traffic volumes and other impacts of the Covid-19 lockdown in Britain. Watch out for further updates


[1] Stradling, S., Fuller, R., Gormley, M., Broughton, P., Kinnear, N. O’Dolan, C. & Hannigan, B (2008). Understanding Inappropriate High Speed: A Quantitative Analysis. Road safety Research Report 93. London: Department for Transport.

[2] International Transport Forum (2018). Speed and Crash Risk, Chapter 2. Speed, speeding and crashes: theory and evidence. Viewed online 9 April 2020, .

[3] Truelove, V., Freeman, J., Szogi, E., Kaye, S., Davey, J., & Armstrong, K. (2017). Beyond the threat of legal sanctions: What deters speeding behaviours? Transport Research Part F: Traffic Psychology and Behaviour, Vol. 50, pp. 128-136.


The graph shown here is from page 74 of The methodology and initial findings for the Road Accident In Depth Studies (RAIDS) Programme: RAIDS Phase 1 Report (PPR808). Cuerden, R. & McCarthy, M. (2016). 

Register for our newsletter

Learn more about TRL with regular updates

Media membership

Our latest press releases and news

Get in touch

Have a question? Speak to one of our experts today.