DETROIT — The head of the National Transportation Safety Board expressed concern on Wednesday about the safety risks posed by heavy electric vehicles when they collide with lighter vehicles.
The official, Jennifer Homendy, raised the issue in a speech in Washington to the Transportation Research Board. As an example, she noted that an electric GMC Hummer weighs about 9,000 pounds (4,000 kilograms), with a battery pack alone weighing 2,900 pounds (1,300 kilograms) — about the full weight of a typical Honda Civic.
“I am concerned about the increased risk of serious injury and death to all road users from heavier curb weights and increasing size, power and performance of vehicles on our roads, including electric vehicles,” Homendy said in remarks prepared for the group.
The extra weight that EVs typically carry comes from the outsized mass of their batteries. To achieve a range of 300 or more miles (480 or more kilometers) per electric car charge, batteries must weigh thousands of pounds.
Some battery chemistries being developed have the potential to pack more energy into less mass. But for now, there is a difference in weight between EVs and smaller combustion engine vehicles. EVs also deliver power directly to their wheels, in most cases accelerating faster than most gas-powered cars, trucks and SUVs.
Homendy said she was encouraged by the Biden administration’s plans to phase out carbon emissions from vehicles to deal with the climate crisis. But she said she is still concerned about safety risks from a proliferation of electric cars on roads and highways.
“We have to be careful not to also create unintended consequences: more deaths on our roads,” she said. “Security, especially when it comes to new transportation policies and technologies, should not be overlooked.”
Homendy noted that Ford’s F-150 Lightning EV pickup is 2,000 to 3,000 pounds (900 to 1,350 kilograms) heavier than the combustion version of the same model. The electric SUV Mustang Mach E and the Volvo XC40 EV, she said, are about 33% heavier than their petrol counterparts.
“That has a significant impact on the safety of all road users,” Homendy added.
The NTSB investigates traffic accidents, but has no authority to make rules. For vehicles, this authority rests largely with the National Highway Traffic Safety Administration.
Even aside from electric cars, the country’s roads are full of heavy vehicles, thanks to a decade-long boom in sales of larger cars, trucks and SUVs that has led to extreme mismatches in collisions with smaller vehicles. But electric vehicles are typically much heavier than even the largest trucks and SUVs that run on gasoline or diesel.
Michael Brooks, executive director of the nonprofit Center for Auto Safety, said he, too, is concerned about the weight of electric cars, as buyers seem to demand a range of 300 or more miles per charge, which requires heavy-duty batteries.
Setting up a charging network to accommodate that could be a mistake from a safety standpoint, Brooks said.
“These bigger, heavier batteries are going to do more damage,” he said. “It’s a simple matter of mass and speed.”
Brooks said he knows little research has been done on the safety risks of increasing vehicle weights. In 2011, the National Bureau of Economic Research published a paper stating that being hit by a vehicle carrying an extra £1,000 increases the chance of being killed in a crash by 47%.
He points out that electric vehicles have very high horsepower, allowing them to accelerate quickly even in congested urban areas. “People are not trained to deal with those kinds of accelerations. It’s just not something drivers are used to doing,” said Brooks.
Also, many newer electric SUVs are tall with limited visibility, posing risks to pedestrians or drivers of smaller vehicles, he said.
Sales of new electric vehicles in the US rose nearly 65% last year to 807,000, about 5.8% of all new vehicle sales. The Biden administration has set a goal of electric cars to make up 50% of new vehicle sales by 2030 and is offering tax credits of up to $7,500 to get there. The consultancy LMC Automotive has made a more modest forecast: it expects EVs to account for a third of the new vehicle market by 2030.