The Nation's roadways have become so overloaded with traffic that they can have an adverse affect on the quality of life for many Americans. According to the Texas Transportation Institute's 2004 Urban Mobility Report, the annual delay per rush hour traveler has grown from 16 hours to 46 hours since 1982, and the annual financial cost of traffic congestion has ballooned to more than $63 billion (expressed in 2002 dollars). Congestion on urban freeways and arterials continues to increase at an alarming rate, the report says, increasing the potential for crashes and long delays, releasing harmful air pollutant emissions, and increasing operating costs.

In past decades, numerous models were developed to simulate traffic flow, evaluate operations and road safety, and optimize control systems. "The tools have become much more useable through better software development in the last 5 years," says John Hourdakis, a research fellow at the University of Minnesota, "and we now have data being collected and archived in new intelligent transportation system applications for analysis."

Despite the widespread use of traffic simulation software, however, opinions on how and which simulation procedures should be used vary among practitioners, making it difficult to replicate and share results. In December 2001, FHWA organized a team of engineers to evaluate many of these new software programs and provide guidance on how to use them effectively. The fruits of their labors culminated in a multivolume Traffic Analysis Toolbox. With the first three volumes already available online, and the remaining volumes due in early 2005, FHWA is providing the leadership and training to help traffic managers use these tools and concepts to improve the Nation's highway system.