Fully autonomous vehicles, which would carry out many or all of their functions without the intervention of a driver, may someday bring sweeping social and economic changes and "lead to breakthrough gains in transportation safety." At present, no fully autonomous vehicles are available for public use. Many new vehicles have automated some driver functions, but all require a human to monitor the driving environment and control the vehicle. However, rapid advances in technology have made it likely that vehicles with high levels of automation will be on the market within a few years, raising questions about the adequacy of existing methods of safety as discussed in chapter 1. For this and other reasons, federal oversight of the testing and deployment of autonomous vehicles has been of considerable interest as reported in chapters 2 and 3. Chapter 4 examines the implications of autonomous vehicles on America's roadway infrastructure.