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Traffic on the Gardiner Expressway, in Toronto, in a June 29, 2015, file photo.Mark Blinch/Reuters

If you’re worried that EVs will cause our already-crumbling roads to crumble even faster, don’t be. Cars had a weight problem long before electric vehicles with their heavy batteries hit the road.

Extremely heavy vehicles such as commercial trucks and buses cause the majority of the wear and tear on roads. Any additional damage caused by the shift to EVs will be so marginal as to be a non-issue – well, unless everyone replaces their Honda Civics with fully loaded 37,000-kilogram Tesla Semi trucks or gargantuan Hummer EVs.

From 1982 to 2004, the average weight of new vehicles in the United States climbed to 1,864 kilograms from 1,452. Since then, the weight gain has been much slower, but the U.S. Environmental Protection Agency (EPA) nevertheless anticipated 2021′s new vehicles would be the heaviest yet, weighing in at an average of 1,944 kilograms.

The situation in Canada is similar, where the average weight of new light-duty vehicles was 1,757 kilograms in 2019, almost 20 per cent more than the global average, according to the Paris-based International Energy Agency. The agency also reports that Canadians drive the largest and second-heaviest set of vehicles in the world.

Even as car design and technology improved – using lighter aluminum instead of heavier steel, for example – the average weight of new vehicles kept rising. The reason, according to the EPA’s 2021 Automotive Trends report, is that, “the market shifted towards car and truck SUVs, which are often larger, heavier, more powerful and less fuel efficient than the sedan/wagons they replaced.”

The problems with our collective love of hefty vehicles are well documented and fairly obvious. They are less energy efficient, they tend to drive and handle poorly and, above all, they make roads more deadly, especially for pedestrians and cyclists. And, yes, more weight also means more road damage, but the scale here is important.

Electric versus gas

“It’s fair to point out that there are challenges with the weight of electric vehicles, and how heavy the batteries are,” said Shoshanna Saxe, an associate professor in the University of Toronto’s department of civil and mineral engineering. “But to say [EVs] are heavy and wearing out roads, it would be disingenuous,” said Saxe, who is also the Canada Research Chair in Sustainable Infrastructure. The real problem, she noted, is heavy vehicles in general.

“Underneath the wheels of a car, the road is bending and cracking,” Saxe explains. “The more you bend and change the shape of things, the more they crack and wear down.” Hence: potholes, ruts, ripples, cracks and the generally poor state of some streets.

The relationship between weight and wear isn’t linear. A series of experiments done in the 1950s found that the change in pavement damage is roughly proportional to the difference in axle weight to the fourth power. So a heavy commercial truck, which might have five axles and a total weight of 50 tonnes (call it 10 tonnes per axle), could do 10,000 times more damage than a mid-sized SUV with two axles and a total weight of two tonnes (or 1 tonne per axle). How did we get there? With an axle load that’s 10 times greater than the SUV, the fourth power formula shows: 10 x 10 x 10 x 10 = 10,000.

Meanwhile, even the heaviest of e-bikes do virtually no road damage at all.

The standard-range Ford F-150 Lightning weighs 2,800 kilograms, which is a lot no doubt, but only by passenger car standards. It’s roughly 240 kilograms heavier than a similar hybrid-powered F-150. That’s nothing compared to a fully loaded commercial semi-trailer, which can weigh more than 50,000 kilograms.

The heinous 4,100-kilogram Hummer EV aside, some EVs aren’t even that heavy by modern automotive standards. The long-range Tesla Model 3 all-wheel-drive is just 38 kilograms heavier than a gas-powered BMW M340i xDrive. And a Hyundai Kona EV weighs 1,750 kilograms, while the gas version tips the scales at 1,434.

Because the majority of wear and tear is done by big trucks and buses, the extra 100 or 200 kilograms some EVs are packing is just a pebble in a pothole.

EVs won’t necessitate more road maintenance because the difference in weight between electric cars and gas ones is relatively minor, a spokesperson for the Michigan Transportation Department recently told the Detroit News.

Who pays?

People driving gas guzzlers might whine that the situation still isn’t fair because EV drivers don’t pay gas taxes, which generate billions of dollars annually to help pay for road maintenance, among other things.

A reasonable person might reply that drivers have never really paid their fair share for the environmental and road damage they do, but that’s another story.

The loss of gas tax revenue as drivers shift to electric cars will be significant, but it won’t happen overnight. It’ll be a gradual process over the coming decades, which means the lost tax revenue can be generated elsewhere. For example, by implementing an annual registration fee based on vehicle size and/or weight.

That, at long last, might at least get drivers who can do so to consider smaller, lighter, more pedestrian-friendly cars.

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