Mile Share can help address the problems communities and transportation districts are facing regarding growing populations and the need for additional incentives for transportation alternatives. Projected growth in VMT could undermine many of the measures being undertaken to reduce air pollution and address climate change. The growth of electric vehicles (which is a good thing) is reducing the funds available from gas taxes for road maintenance and improvements.

Limits on VMT present many problems for urban planners. Americans are used to having roads be “free.” The “open road” is as American as apple pie. Limits to VMT are associated with loss of freedom, and tracking people’s movements is associated with loss of privacy. VMT patterns of usage also vary by income and geography. Some cities have water features necessitating the use of bridges. Housing prices, land use, zoning, and other economic factors can result in lengthy commuting patterns. As with other Commons that are shared, in many cases wealthier portions of the population may use more than average. Wealthier drivers in the exurbs may desire to buy additional Mile Shares from lower income individuals who take transit or carpool. In this way, Mile Share may counteract the regressive impacts of fuel taxes. However, a study of land use, employment and commuting patterns, and transportation alternatives for particular communities considering implementing a Mile Share program is recommended.

Metropolitan (more urban) counties could use a regional distribution to account for cross-county driving patterns, while rural counties may prefer distribution within a single county. If implemented at a State level, program administrators should address the potential for resentment between urban counties which might have to purchase VMT and rural counties. Therefore, if allocations differ between urban and rural counties, in certain situations it may be prudent to set the VMT caps at the county level and limit trading of Mile Shares to drivers residing in the same county.

Regressive Impacts: A VMT cap would have mixed effects on low-income households, depending on several factors, including the number of drivers in the household, the number of vehicles, and their location. Some low-income workers have longer commutes and less flexibility in their housing location, job choice, and mode of transportation than higher income workers. On the other hand, in some areas high-income households have chosen to live in exurbs away from employment centers, and could afford to pay for the additional social costs of those choices. Some high-income workers may have more options to reduce their VMT, for example, by telecommuting. The increase in rents near employment and mixed-use centers would also disadvantage low-income households. On the plus side, low-income households that used more transit, alternative modes, and drove less could sell part of their excess VMT Share, and income from the Share would benefit low-income households more as a fraction of their income.

Jurisdictions may be interested in customizing the Mile Share program, to include fees for road maintenance and repair, or to provide additional incentives to regular transit users. Program administrators would have to decide how the system would apply to the commercial sector, where there may not be as many alternatives to reduce vehicle miles traveled.