Increasing Transportation System Efficiency
Taking Climate Change into Account in U.S. Transportation
Increasing Transportation System Efficiency
System efficiency can be improved by increasing the use of energy-efficient modes of transportation. Increasing the efficiency of particular modes, and increasing accessibility through denser land use patterns that facilitate alternative modes such as walking, biking, and transit, would both decrease GHG emissions.
Despite very large differences in the energy intensities of freight modes, attempts to shift to more energy-efficient modes, such as from truck to rail or from rail to water, run counter to increasing requirements for speed and reliability. The greatest opportunity for improving freight efficiency may lie in providing infrastructure that allows freight to be quickly, efficiently, and inexpensively transferred among modes.
For passenger travel within the United States, energy use per passenger is similar across modes in large part because transit occupancy rates are low. A suite of policies could promote the use of transit and ease inter-modal transfers.
Transportation demand is influenced by the geographic distribution of people and places, especially the density of development and zoning. Studies have shown that a combination of land use and transit policies might succeed in reducing vehicle miles in large urban areas by 5 to 10 percent over thirty years, if combined with policies to charge for parking and for use of congested roads. Vehicle travel might be reduced by 10 to 25 percent by changing the design of subdivision development to accommodate walking and cycling and mixed land uses to reduce the need for motorized trips.
Land use and transportation infrastructure policies will have little immediate impact on GHG emissions, but could be among the most important policies in the long run. Investments in transit infrastructure and land use policies favoring transit-oriented development not only reduce automobile trips, but also increase transit occupancy rates and density of development. Moreover, there are other benefits from more efficient land use, including reducing traffic congestion, protecting habitats, and improving air quality.
Policy options for increasing transportation system efficiency include:
- Investment and incentives for more efficient transportation modes. For instance, funding could be increased for highly efficient rail systems or Bus Rapid Transit (BRT). Another way to encourage more efficient modes would be to increase the amount employers are allowed to provide to their employees for transit fare on a tax-free basis, and to extend the benefit to commuters who walk or bike. This would balance the untaxed parking benefits many employers provide. It would also save the employers money since they do not have to pay payroll taxes on the amount of employee income excluded under such benefit plans.
- Investment in intermodal infrastructure. This would provide funding for infrastructure that facilitates the transfer of freight and passengers between modes of transportation, such as rail lines to ports, transit lines to airports, and better parking facilities and car-sharing services at transit stations. Providing alternative revenue sources for airports might be especially important, given that many airports now derive half of their revenue from their parking garages.
- Allowing highly efficient vehicles on HOV lanes. Highly efficient vehicles could be granted special access to High Occupancy Vehicle lanes.
- "Smart growth" policies. Integrating land-use and transportation planning would help to minimize sprawl and promote easy access to public transit.
- Intelligent Transportation Systems. Computers and global positioning satellites are already being used to route long-haul trucks more efficiently. Intelligent transportation systems may save both time and energy by finding the most efficient routes for auto and transit users as well.
- Use of climate-friendly materials. Using recycled materials in road-beds or for road surfacing could reduce GHG emissions. For example, substituting coal fly ash for cement can significantly reduce greenhouse gas emissions. Every ton of coal flyash substituted for cement reduces life-cycle GHG emissions by almost a ton.9 The adoption of performance measures for pavement, for example under the Interstate Maintenance and Bridge program, would be one policy option. Requiring the use of longer-lasting pavement could also reduce congestion caused by work zones for repaving roads and filling potholes.