bill introduced by Chairman Rockefeller of the Senate Commerce, Transportation, and Science Committee and Senator Lautenberg (S. 1036) calls for annual reductions in per capita vehicle miles of travel, a 40 percent reduction in transportation GHG emissions by 2030, increased use of public transportation, and an increase of 10 percent in the proportion of freight moved on nonhighway modes. In addition, various states have adopted plans to reduce future vehicle miles of travel.

As described in Chapter 3, the effectiveness, costs, feasibility, and acceptability of most strategies to mitigate transportation GHG emissions have not been established. Because travel and economic growth are tightly linked, implementing the most cost-effective mitigation policies would help minimize reductions in future prosperity. The federal government, states, MPOs, cities, and counties will all set transportation policies. Thus, the audience for transportation policy guidance is large and diffuse. The research areas identified in Chapter 3 would provide guidance for policy decisions at all levels of government.

The climate will continue to change for decades because of GHGs already in the atmosphere. Therefore, well-designed adaptation to climate change needs to begin. The infrastructure capital costs of raising or replacing bridges, roads, and guideways vulnerable to flooding, for example, are high, and climate impacts at the spatial and temporal scales that transportation officials require cannot be predicted. The recommendations in Chapter 4 provide a framework for conducting research that can guide decisions about effective transportation adaptation strategies.


The committee believes that the urgency of responding to energy and climate change goals requires initiation of the research identified in previous chapters in short order. The technical information to inform policy decisions and practice could be significantly enhanced over the course of the next surface transportation authorization cycle, although at least two such cycles would likely be required to complete the envisioned fundamental and applied research. Some of the recommended research will probably need to continue on a regular basis, much as safety, operations, and other subjects are ongoing topics of research.

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