Estimates of Work Zone Exposure on the National Highway System in 2001

A comprehensive set of data on work zone exposure characteristics does not exist at the national level. Without accurate work zone exposure data, it is impossible to know whether changes in work zone performance measures (safety, congestion, public sentiment) over time are due to true changes in the characteristics of work zones or to changes in external factors. Presented are the results of a study exploring the quality and quantity of work zone data available in the United States. During this study, researchers collected data in five regions across the country. The regional data were then extrapolated to develop national estimates of several work zone exposure characteristics on the National Highway System (NHS) during 2001. Researchers examined constructionmanagement databases, traffic control plans, and project-inspector diaries on projects performed by private contractors in these regions during 2001. Researchers also gathered data on work zone activities that were performed directly by transportation agency in-house personnel in each of the regions. These data were then extrapolated to national estimates of several work zone exposure measures during the 2001 calendar year, including the percentage of NHS that experienced at least 1 day of work zone activity in 2001; length, duration, and frequency of activity in work zones on the NHS; impacts of work zones on available NHS roadway capacity; and vehicle exposure to active and inactive work zones on NHS during the year.