Despite significant advances over the past few decades, road collisions claimed over 1,600 lives in the UK in 2023, with over 28,000 people suffering serious injuries. Several strategies have aimed to tackle this; such as design enhancements, technological advancements and safety campaigns, however since 2010 there has been no significant reduction in fatalities and serious injuries on the UK’s roads.
An FTVG project team formed of designers, engineers and academics decided to look at whether car weights could be having an impact on these casualty figures.
“We decided to choose this angle because it didn’t seem like much research had been done around the relationship of vehicle weights and collision severity”, summarised Ruth Carlson, a design engineer at the London Borough of Camden, “I read some research in Transport & Environment which said that sales of larger cars has been increasing in the UK and wondered whether this had any impact on road safety.”
The project aimed to investigate this relationship by analysing data from 2019 – 2023 to understand how car weight impacts on the severity and likelihood of collisions.
The group realised that obtaining reliable data on vehicle weights was going to be a challenge. As the project evolved, the focus shifted from data analysis to data collection and validation.
“We originally approached the Department for Transport for the car weight data, but unfortunately there was a high amount of missing information”, explains Dr. Nima Dadashzadeh, an Assistant Professor in Transport and Business Analytics at the University of Huddersfield, “We tried several avenues before purchasing data from a reputable 3rd party supplier who purchase their data from the UK Driver and Vehicle Licensing Agency (DVLA).”
The group were then able to analyse over 3,000 fatal collisions from 2019-2023 in the UK involving cars, pedestrians and cycle users, and categorised the cars involved in the collisions into different weight categories. They compared the proportion of fatal, serious and slight collisions for each weight class and also the percentage of fatal collisions in each weight class and compared that to the percentage of registered cars in that weight category on UK roads.
Based on the sample they collected, the group found that people driving heavier cars are disproportionately involved in more fatal collisions. For collisions between cars and pedestrians where at least one pedestrian was the collision victim, the heaviest weight category cars (2001-2500kg) are involved in 62% more fatal collisions than the lightest weight category cars (500-1000kg) per million cars in that weight category.
They produced several breakdowns of this data, examining different types of collisions (such as car on car collisions, as well as car on pedestrian/car on bike collisions).
Separately, the group also demonstrated that the average weight of cars in the UK was increasing from 2014 – 2023. Across all registered cars in the UK, the average increase in car weight was 70kg, whilst there was a bigger increase when looking just at new cars, which had an average increase of 190kg each.
“What we have is a proof of concept for other people, councils, or academics who need vehicle statistics going forward and want to influence road safety policies and vehicle manufacturing standards” said Ruth, “There’s much more to analyse but we hope to develop this into an academic paper in future.”
The research has already been presented at the launch of the Sports Utility Vehicle (SUV) Alliance at the House of Lords and the group hope to showcase their work at other conferences in future.
“We’re keen to emphasise that this is a discussion around weight, rather than a particular car model or body type” explains Nima, “This avoids some politicisation around certain types of cars and enables us to facilitate further discussions more easily.”
Ruth agrees that the messaging of the findings will be important for the project to leave a lasting legacy;
“Motonormativity is strong in our culture and people are very attached to their cars, by categorising cars by weight, it takes away some of the ‘personality’ and the analysis becomes more reliable, and palatable for a car-reliant nation like the UK”, she said.
As well as an academic paper, the group are also aiming to add a human side to their findings;
“I would like to bring engineers closer to the infrastructure they create through a series of short films telling the stories of how the highways make people feel”, outlines Nima, “This could tell a story of a child on a scooter, and how a smooth footway makes them feel free, or it could tell a story of how a woman experiences cycling in the city and how the road danger and imbalance of power on the road makes them feel insignificant and scared.”
A summary paper of the group’s work can be found here: Investigating the relationship between car weight and fatal collision rates – alongside its Appendices.