	Traffic Safety Trends

There are several ways to measure traffic safety: the number of highway fatalities; the number of serious injuries from crashes; the economic loss to people involved in crashes; and the social cost of emergency response and accident-induced traffic delays. In contrast, crashes involving injuries or property damage may be reported inconsistently by local public safety agencies or may not come to the attention of authorities; reported data on the numbers of serious crashes and of crashes involving injuries are estimated based on sampling. Although the fatality rate from motor vehicle crashes has fallen to a record low, other measures indicate that improvement in traffic safety has stalled. Over 90% of the persons killed in such crashes are occupants of the other vehicle(s) rather than occupants of large trucks (see Table 3 ), so the decline in fatalities in crashes involving large trucks is likely due at least in part to improved crashworthiness of cars and light trucks (see Table 3 ). At least three in five bicyclists killed in crashes were not wearing helmets. Engineering

Federal involvement in engineering has proceeded by way of establishing standards for highway and vehicle designs and funding safety-related improvements in highway infrastructure. Road Design

The way roads are designed has a significant impact on their safety. One of the core highway formula programs is the Highway Safety Improvement Program, which provides funding to eliminate hazardous road locations or features. NHTSA spent $130 million to oversee motor vehicle design and engineering in FY2015. The theory that vehicle safety improvements lead drivers to drive in a riskier manner—variously called the Peltzman effect, risk compensation, or risk homeostasis—does not appear to apply to seat belt use; studies have found little or no evidence that belted drivers are more likely to be involved in a crash. NHTSA has estimated that vehicle safety technologies are responsible for roughly half of the reduction in the risk of death for vehicle occupants between 1960 and 2012, with "everything else," which includes social and demographic changes such as those previously discussed, improved road designs, efforts to make drivers drive more safely, and improvements in emergency medical response, accounting for the other half. In large part this is because the vast majority of crashes are due to driver behaviors such as driving while intoxicated, driving too fast for conditions, and becoming distracted, and these are errors of judgment rather than of ignorance or lack of skill. This may reflect, in part, a growing deference to state discretion on the part of Congress in the area of traffic safety, though there is also evidence against that interpretation; Congress has, for example, taken away state discretion to use federal highway funding to support automated traffic enforcement, forbidding states to use any of their federal highway funding for that purpose. There was also a one-time grant to encourage states to adopt a primary enforcement law. Factors such as rural versus urban population, road conditions, and economic activity, as well as state laws and programs and socioeconomic factors, affect the rate of DUI activity. Excessive speed has been shown to increase the likelihood of crashes. As noted above, Congress enacted a penalty for states lacking a universal motorcycle helmet law in 1966, but repealed it in 1975. Policy Options for Further Safety Improvements

Although U.S. highway safety statistics have steadily improved, there is room for further improvement. Since 2010 the reductions in U.S. fatality and injury rates have stalled, and preliminary estimates indicate that traffic deaths increased by 9% in the first nine months of 2015 compared to the same period in 2014, while VMT increased by less than 3%. These include actions dealing with seat belt usage, motorcycle helmets, automated traffic enforcement, and implementation of new vehicle safety technologies. Accelerating Deployment of Increasingly Autonomous Vehicles

Since driver error plays a major role in traffic crashes, the prospect of reducing the role of the human driver in driving decisions is considered to have great potential to reduce crashes and the resulting deaths and injuries.
In 2013, 32,000 Americans were killed in crashes involving motor vehicles. Motor vehicle crashes are a leading cause of death for Americans overall, and the number one cause of death for teenagers. Millions of people are injured in crashes annually, and motor vehicle crashes are estimated to have cost some $242 billion in 2010 in lost productivity, medical costs, legal costs, property damage, and time lost in congestion caused by crashes.
The number of people killed in crashes has declined significantly over the past decade. The reasons for this sharp decline are not entirely clear. While traffic safety agencies have attributed it, at least in part, to their safety efforts, it is in line with a general trend: as measured by the number of miles people are driving, the rate at which people are killed in traffic crashes has been declining steadily since records began to be kept in 1929.
Congress has played a role in improving highway safety. Making road travel safer was one of the responsibilities Congress gave to the federal Department of Transportation (DOT) when it created the department in 1966. Congress has directed DOT to improve the safety of automobile design and of road design, as well as to support programs to improve driver behavior.
An oft-cited statistic in traffic safety is that as many as 90% of road deaths are due at least in part to driver error or misbehavior (such as driving too fast for conditions or driving while drunk or distracted). Driver behavior is a state, not federal, matter; in an effort to address it, Congress has enacted programs that encourage states to pass laws to promote safer driving. The role of driver behavior versus road design and traffic management is a subject of debate. Some analysts note that road designs and traffic management arrangements often allow, or even encourage, driver error and misbehavior, and so play a larger role in crashes than is often recognized. One of the core highway capital improvement programs Congress has authorized is intended to fund safety improvements to highway infrastructure.
A federal study estimated that half of the improvement in highway fatality rates since 1960 was attributable to improvements in vehicle safety technologies, with social and demographic changes, driver behavior interventions, and improvements in road design playing smaller roles. Most of the vehicle safety technologies analyzed in the study increased the likelihood that vehicle occupants would survive a crash. More recently, technological development has focused on preventing crashes. While some crash-prevention technologies, such as automatic braking and lane departure warnings, are available now, others, such as vehicle-to-vehicle communication and vehicles that can operate without human intervention, are not yet on the market. Given that most vehicles remain in use for many years, it may be a decade or more before the majority of cars on the road incorporate those new technologies.
There is opportunity for further improvement: crash and injury rates are no longer declining, and preliminary estimates indicate the fatality rate increased significantly in the first nine months of 2015. Several other nations have significantly improved their highway safety rates in the past few decades, surpassing the U.S. rates. Policy options that might further reduce traffic crashes, injuries, and fatalities include encouraging states to adopt stronger laws regarding use of seat belts and motorcycle helmets, encouraging the use of automated traffic enforcement to reduce speeding and failure to stop at red lights and stop signs, and accelerating the deployment of new vehicle safety technologies. Motorcycle helmet laws and automated traffic enforcement have encountered public opposition.