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50 CHAPTER 5 Recommended Work Zone Crash Data Elements, Collection Techniques, and Analysis Methods Introduction Lack of work zone information, Lack of identification of work zone limits, Highway agencies are beginning to recognize the value of Lack of ability to know whether or not the work activity having access to comprehensive crash and other supporting had any effect on the crash, and (i.e., exposure) data for work zones. These data can be used Lack of identification and assessment capabilities of worker to develop work zone crash rates and to assess work zone injuries/fatalities. operating characteristics such as traffic, delays, and travel speeds/times. These crash rates and operating characteristics could be used by the agencies to determine statewide work Categories of Critical Data Elements zone safety and mobility trends and/or the need to modify or While a number of state crash reporting forms include a enhance work zone traffic control plans. way to identify work zone crashes--and a few do include FHWA rulemaking finalized in 2004 increases the impor- some additional fields to capture work zone characteristics-- tance of this issue. Specifically, it requires highway agencies to most do not obtain sufficient information to fully assess the collect and analyze work zone data, including crash data (71): relationship of a crash to common work zone features. A num- (c) Work zone data. States shall use field observations, available ber of suggestions have been made by state highway agencies work zone crash data, and operational information to manage as to the types of safety performance measures that would be work zone impacts for specific projects during implementation. useful in assessing and comparing work zone crash experi- States shall continually pursue improvement of work zone safety ences and improvement initiatives (74): and mobility by analyzing work zone crash and operational data from multiple projects to improve State processes and proce- Crashes per day of work activity per hours of work; dures. States should maintain elements of the data and informa- tion resources that are necessary to support these activities. Crashes per day the work zone traffic control is in place; Crashes per work zone mile; Previously, highway agencies and others have indicated a sig- Crashes per type of work zone or work zone activity; nificant concern that police accident reports frequently do not Crashes per vehicle-miles traveled; accurately or consistently indicate work zone involvement in Crashes per million entering vehicles; and traffic crashes, which can significantly impact the results of any Number of crashes per location in work zone (e.g., num- analyses performed on that data (72, 73). The majority of police ber of crashes in queues, number of crashes in the advance crash report forms used by states now include some explicit field warning area, etc.). or code to identify whether a crash occurs within the limits of a highway work zone. However, although some improvements in However, the ability to perform a meaningful analysis is crash reporting for work zones are evident, more is still needed. based on the availability of sufficient data that adequately de- Highway agencies have expressed a number of concerns re- scribe the crash and the characteristics of the work zone garding work zone crash data, which can generally be grouped where it occurred, as well as other information about the into the following categories: project and traffic characteristics. Some of the types of data considered desirable include: Lack of consistency and accuracy of police crash databases, Lack of interoperability between databases, Description of the traffic control devices in the area of the Lack of timely data, crash;