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OCR for page 79
79 SECTION X Reducing Crashes in Work Zones The FHWA rule on work zone safety and mobility (31) through the work zone. This includes crashes occurring on ap- specifies that each agency "develop and implement system- proach to, exiting from or adjacent to work zone that are related to the work zone (31). atic procedures to assess work zone impacts in project development and to manage safety and mobility during Analysis of work zone crashes will be discussed in terms of the project implementation." This rule states that agencies "shall existence of three items or data files. continually pursue improvement of work zone safety and mobility by analyzing work zone crash and operational data 1. The existence of an item on the crash record that identi- from multiple projects" (31). fies the crash as a work zone crash. It is recommended that Strategies to reduce work zone accidents can cover a broad this work zone crash identifier be an explicit item that spectrum of the roadway system. Every freeway, rural road or must be completed, if applicable, for each crash, rather city street will at sometime in its life cycle be in a work zone. than being one of many possible contributing circum- These work zones can vary in duration from a 1-hour crack stances that might be noted in a field such as "roadway sealing location, to a complete reconstruction lasting months defects." or years. Exposure of road users to work zones is extremely 2. A work zone or project file that lists the location and dates difficult to measure and has been the subject of several of various work zones. This file may only contain data on research projects. construction projects of long-term duration, or may also The work zone crash history is often similar to the crash include short-term maintenance and utility work zones. experience of the roadway prior to work. It is recommended 3. Computerized roadway inventory data including traffic that the crash history of the roadway be reviewed as part of count data that can be linked to the crash data by location the work zone design process. While all crashes that occur of the crash. during a work operation may be termed "work zone" crashes, it may be beneficial to examine other guides for reducing As discussed in Appendix 9 of A Guide for Reducing Work crashes in a specific area. For example, if there are a large Zone Collisions (17), the Model Minimum Uniform Crash number of single vehicle run-off-road crashes, the guide for Criteria (MMUCC) recommends that four fields be collected reducing run-off-road crashes should be consulted. on work zone crashes as follows: Many agencies specify that project engineers collect data on work zone crashes that occur on their projects. While this 1. Was the crash in or near the construction, maintenance, procedure ensures that project personnel are aware of crashes or utility work zone? If yes collect fields 24. taking place on their project, and analyses of these crashes 2. Location of the crash: may supplement other analysis, they do not involve the crash a. Before the first work zone sign records system and therefore are not discussed in this guide. b. Advance warning area In the FHWA rule on work zone safety and mobility the c. Transition area definition of work zone crash is as follows: d. Activity area e. Termination area Work zone crash means a traffic crash in which the first harm- ful event occurs within the boundaries of a work zone or on an 3. Type of work zone: approach to or exit from a work zone, resulting from an activity, a. Lane Closure behavior, or control related to the movement of the traffic units b. Lane shift/crossover