Increases in vehicle weight cause a spike in the rate of fatalities, studies show.
ByLloyd Alter Lloyd AlterDesign EditorLloyd Alter is Design Editor for Treehugger and teaches Sustainable Design at Ryerson University in Toronto.Learn about our editorial processUpdated April 14, 2022 03:21PM EDTFact checked byKatherine Martinko Fact checked byKatherine Martinko
Katherine Martinko is an expert in sustainable living. She holds a degree in English Literature and History from the University of Toronto.
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We've regularly covered two themes on Treehugger: how light trucks (SUVs and pickups) are deadly, especially to pedestrians, and how weight matters in electric cars. Now, Kyle Stock of Bloomberg puts the two themes together in what, in retrospect, seems totally obvious: With their greater size and power, battery-powered SUVs and pickup trucks are heightening pedestrian safety concerns.
Stock points to a study, "Pounds that Kill: The External Costs of Vehicle Weight," which found: "Controlling for own-vehicle weight, being hit by a vehicle that is 1,000 pounds heavier results in a 47% increase in the baseline fatality probability. Estimation results further suggest that the fatality risk is even higher if the striking vehicle is a light truck (SUV, pickup truck, or minivan)." This was written in 2011—long before electric cars and trucks were part of the calculations.
Another more recent study said, "Metropolitan areas with more growth in large vehicles suffered greater rates of pedestrian fatalities." While large vehicles make the drivers safer, "less concern is given to the effect on pedestrians."
The problems for the pedestrians are two-fold: "First, the additional weight means the vehicle will take longer to come to a stop and will strike with more force as compared to a lighter vehicle. Second, large vehicles have higher front ends, affecting the point of impact on a pedestrian."
Study author Justin Tyndall tested for body design and also for weight, finding:
"Every 100 kg increase in average vehicle weight is associated with an additional 0.03 fatalities per 100,000 residents. The median observation has an annual pedestrian fatality rate of 1.34 fatalities per 100,000 residents, meaning that a 100 kg increase in average vehicle weight is related to a 2.4% increase in pedestrian fatalities for a metro with the median fatality rate."
According to CNN reporter Peter Valdes-Dapena, the Ford F-150 Lightning weighs 1,600 pounds, or 726 kilograms, more than the gas-powered version. At 2.4% per 100 kilograms of vehicle weight, that would make the electric truck 17.4% more likely to kill than the gas versions. Other factors do come into play, such as bigger brakes; back at Bloomberg, carmakers and experts poo-poo the idea that they are going to be more dangerous.
"Electric cars tend to have better weight distribution and lower centers of gravity than gas-powered cars, thanks to the ponderous battery sealed under the floor of the machine, so braking power is spread more evenly among the four wheels and the tires have more friction with the road. “It all counteracts the additional momentum,” Jake Fisher, an engineer who leads auto testing at Consumer Reports, told Bloomberg. “In a physics equation, it cancels out.”
I am not convinced. In a separate study, Blake Shaffer of the University of Calgary noted the increase in weight of the truck "rivals the climate benefits of avoided greenhouse gas emissions." Shaffer reminds us that weight matters: "Without addressing the weight issue, the benefits for society of going electric will be smaller than they could be in the next decade."
Shaffer commiserated about getting complaints regarding the perfect being the enemy of the good after discussing the issue of size and weight of electric vehicles. He told Treehugger:
"Yes, it’s always challenging writing a critique, even a partial one, about EVs. Either one side is mad at you for 'not caring about the environment,' or another is using your words in bad faith to unfairly push back on the transition. We really tried to emphasize the 'win-win' story for electric vehicles, i.e. making them clean and safer/lighter."
But all the evidence demonstrates that vehicle weight and size matter, whether it is the embodied carbon from making them, the extra resources to make the batteries, the extra electricity to fill them, or, now, the extra danger for pedestrians around them.
