In Europe, 69% of pedestrian fatalities occur in urban areas, where speeds of 15 – 30 km/h are typical, and where lower speed limits (e.g. 30 km/h) are increasingly being adopted for given streets, roads or city areas. High bonnets are comparatively worse for pedestrians when they are struck by vehicles moving at speeds up to around 50 km/h, a point also made by Ptak. At higher speeds, the chances of survival drop for pedestrians struck by all vehicles, irrespective of bonnet height (as speed is of greater relative importance in high-velocity crashes). In short, the mitigating effects of lower bonnets would be most apparent in urban areas where more than two-thirds of pedestrians are killed.
European crash literature
The increased danger of higher bonnets was outlined in August 2023 as part of a major longitudinal study by VIAS, a Belgian institute specialising in road safety. VIAS analysed collisions in Belgium between 2017 and 2021, a sample cohort involving 300,000 road users in total.
The crash data studied by VIAS shows that a 10 cm increase in bonnet height (from 80 cm to 90 cm) raises the risk of death by 27% for vulnerable road users. In the VIAS study, VRUs comprise pedestrians, cyclists, motorcyclists and scooter riders. VIAS also found that when high-fronted SUVs, such as pick-up trucks, crash into regular cars, they impose 20 – 50% more risk of serious injuries on the occupants of the regular cars.
To better protect vulnerable users, VIAS stresses that the trend to higher bonnets must be arrested. Overall, the VIAS study presents a strong European research case to prevent and reverse ever-rising bonnet height.
Euro NCAP notes that “the shape of the hood or bonnet leading edge can play a critical role in the outcome of a vehicle impact with a pedestrian and contribute to injuries”, and highlights that its test procedure “promotes energy absorbing structures and a more forgiving geometry that mitigates injuries”.
High-fronted SUVs can offer relatively low protection to a pedestrian’s pelvis. For example, Euro NCAP testing on the leading edge of the Land Rover Defender’s bonnet, which is 115 cm high, “revealed poor protection to a pedestrian’s pelvis at nearly all points across [its] width”. NCAP also found that the same vehicle is also among those with elevated crash aggressivity towards regular cars, i.e. highly damaging in collisions with typical mid-sized family cars.
Euro NCAP’s testing and rating focuses on avoiding and mitigating primary injuries, i.e. as the vehicle first strikes the pedestrian. Assessing the likelihood, and likely severity, of secondary injuries – i.e. as the pedestrian later hits the ground, or is struck again by the vehicle – can be more complex.
However, the literature has assessed both primary and secondary injuries by using modelling and analysing real-world collisions. And overall, the literature echoes the VIAS findings (summarised above) regarding vulnerable road users, most particularly for pedestrians. Reading the literature, it is clear that:
The centre of gravity of lower-height females (5th percentile) is 86 cm. While it is lower for younger children, the centre of gravity in average height 11 to 12 year olds is comparable to the 5th percentile adult female. In other words, if bonnet height in vehicles produced after a certain date was limited to 85 cm, it would help protect almost all females and offer at least some protection for children from the age at which most will be walking independently. Or, put another way, the more bonnet height exceeds 85 cm, the more adults and children are at greater risk.
In short, danger to other road users rises with increased bonnet height. High-bonneted vehicles are linked to increased rates of death and serious injury in other road users. While we have focused most here on vehicle-to-pedestrian crash severity, similar issues – and increased risks – arise for cyclists and other vulnerable road users. Occupants of regular-sized cars are also at greater risk from high-fronted SUVs, as shown by the VIAS study.
Higher bonnets mean more children not seen
As well as increasing collision severity, higher bonnets reduce vision, particularly of children. Reduced driver vision risks increasing the frequency of collisions, and / or near miss situations.
Children are disproportionately killed as pedestrians in road traffic collisions. Of the approx 430 children killed a year on Europe’s roads, 31% die as pedestrians, compared to 18% when all age groups are taken together.
Linked to work by Clean Cities on child-friendly cities, T&E commissioned tests to better understand the extent to which drivers in high-bonneted SUVs can see children to the front. This analysis was undertaken by an expert in direct vision, Dr Steve Summerskill at the Loughborough School of Design and Creative Arts (SDCA).
Summerskill assessed the visibility of children of average European height standing in a central position at the front of two well-known high-bonneted vehicles, the RAM TRX and the Land Rover Defender, and one regular car, the VW Golf.
The RAM TRX was chosen as one of highest-fronted light duty vehicles sold in Europe. RAMs are not type approved for the European market, but are registered under Individual Vehicle Approvals (an approval route which is often problematic, and due to be tightened, at least in the EU). The leading edge of the RAM TRX’s bonnet is close to 130 cm high and an elevated area nearer the windscreen also contributes to obscuration by raising the line of vision above the bonnet edge, as shown below. At 115 cm, the Land Rover Defender is understood to have the highest bonnet of European-made models.
On the other hand, the VW Golf, with a bonnet height of 75 cm, is intended to act as a proxy for other vehicles with bonnet heights of 60 to 75 cm, which follow best practice in the design of vehicle fronts, according to the literature. Other vehicles with bonnet heights of 60 to 75 cm include the Audi A1, BMW 4 Series, Hyundai Ioniq, Kia Ceed, Mercedes Benz CLA, Opel / Vauxhall Astra, Porsche Taycan, Seat Leon, Skoda Fabia, Tesla Model 3 and Tesla Model Y.
Seated behind the steering wheel of a RAM TRX pick-up truck, a driver of average European adult height cannot see children of average height standing in front aged up to, and including, nine years old. Average height drivers in Land Rover Defenders cannot see children aged up to four-and-half standing in front.
