The Biden administration today announced a new environmental regulation that forces manufacturers of heavy trucks to quickly transition their new vehicles to electric power or other low-pollution technologies.

Together with a similar regulation on passenger cars issued last week, the new rules represent the administration’s most significant effort to transform the transportation industry, which is the nation’s largest source of fossil fuel emissions.

The new rule does not mandate the use of electric motors, but rather sets increasingly strict emissions limits across manufacturers’ production lines. Officials project that it will increase the percentage of new nonpolluting long-haul trucks sold in the U.S. from 2 percent to as much as 25 percent by 2032.

But that won’t be cheap or easy. The shift to electric trucks lags far behind the adoption of electric personal vehicles, in part because electric eighteen-wheelers can cost two or three times as much as a diesel truck and require large, heavy batteries that reduce the truck’s capacity. Also, there are currently only 5,000 charging stations in the U.S. capable of serving heavy trucks, far fewer than what truckers say would be required to make the transition.