A road charge is a per mile charge for operating a motor vehicle on the public roads. It is intended to be a replacement for the gas tax, as gas tax revenues decline with the shift to electric motor vehicles (CalMatters: California gas tax revenue will drop by $6 billion, threatening roads). The state website is California Road Charge.

Road charge is not a tolling system. It charges per mile driven, no matter what the classification of roads (freeway, arterial, collector, local). The California gas tax funds maintenance of mostly large infrastructure, bridges and freeways, but to a lesser degree surface arterials, collectors and local roads. In every place in California, the gas tax, as well as motor vehicle fees, pays for only about half of the cost of roadways. The rest is paid for at the county and city level, by all taxpayers regardless of how much they drive, or even if they drive. As such, transportation funding is in part a subsidy to motor vehicle drivers by people who don’t drive. The same is true at the federal level, where gas tax accounts for less than half of the highway trust fund. The inflation adjusted yield of federal gas tax has been declining since 1994.

A road charge, which drivers pay when they actually use the roadways, is an equitable system because every driver can choose, to some degree, to drive more or less. Though many low income people live in locations where access to jobs and other destinations is difficult without a car, there is always some choice involved. That doesn’t mean there are no equity implications, but a road charge is definitely more equitable than the gas tax because high income people can afford higher gas mileage or electric vehicles, whereas low income people cannot.

Many road charge proposals charge all vehicles the same per-mile rate. This is not equitable. The damage to pavement, and the pollution generated by tire and brake wear, is directly related to the weight of the vehicle. Big rig trucks cause many times more damage to roadways, and produce many time more tire and brake dust, than passenger vehicles. And large SUVs, so popular these days, also produce much more roadway wear and tear and tire and brake dust. And of course since electric vehicles weight considerably more than fossil fuel vehicles, they also produce more. Therefore, road charges should be ‘weighted’ by the weight of the vehicle. This information is available for every vehicle, as it is required when registering; yes, people can modify to create heavier weight, but the initial weight is close enough. Caltrans claims that all vehicles under 10,000 lbs GVW cause the same amount of road damage, even the elephantine electric Hummer, but this doesn’t pass the smell test. The standard calculation is that road wear goes up as the square (conservatively; fourth power is well documented for heavy trucks) of the weight. So the Hummer (9500 lbs) causes about 100 times the damage of a Prius (3000 lbs). Even at the conservative second power, it causes 10 times as much damage. Heavier vehicles of course also require that bridges be built for heavier loads, increasing their built cost as well as maintenance.

California has carried out one road charge pilot, a demonstration for different charging mechanisms, and is soon to start another pilot. It is hard to say when a road change might be implemented across the state. It has a lot of opposition from drivers who think the roadways should be free and that others should pay instead, or that gas tax covers infrastructure needs, which is only partially does.

San Diego County (SANDAG MPO) was slated to start a road charge for that county, but the board chickened out and removed it from the regional transportation plan draft. However, it is unlikely the plan will be accepted by the state unless it is either returned, or a viable alternative is proposed (KPBS: SANDAG board nixes ‘road usage charge’ from transportation plan).

It is a universal truth that drivers don’t want to pay the true cost of their driving. An appropriately designed road charge comes closer to the true cost than anything else.

A reminder: A road change is different from tolling/pricing. The road charge applies to all roadways at all times. Tolling applies to high cost infrastructure such as bridges and freeways, and may vary with time or other criteria.