This research project focused on assessing the effectiveness and essential role of flaggers and spotters in directing traffic for expressway and freeway work zones in Illinois with a posted speed limit greater than 40 mph. The objectives of this project were to (1) conduct a comprehensive literature review to study the latest standards and research on the use of flaggers and spotters to direct work zone traffic on expressways and freeways; (2) perform site visits and field studies to evaluate flagger practices currently used in work zones in Illinois; (3) collect and fuse the latest data on work zone crashes in Illinois during a 14-year period from 1996 to 2009 from all available sources; (4) analyse the gathered data to study the frequency and severity of traffic-related work zone crashes in Illinois highways, and investigate the probable causes and contributing factors of these work zone crashes; (5) investigate the feasibility and effectiveness of work zone safety measures that can be used to supplement or replace the use of flaggers and/or spotters, such as intrusion alarm systems, portable changeable message signs, and portable speed monitoring displays; (6) conduct an online survey of resident engineers and construction personnel in the Illinois Department of Transportation (IDOT) and other state DOTs to gather their feedback on the essential roles and effectiveness of flaggers and spotters in directing work zone traffic for expressways and freeways; (7) identify the effectiveness and risks of using spotters and/or flaggers in work zones with a posted speed limit greater than 40 mph on Illinois expressways and freeways, and identify effective work zone safety measures that can be used to supplement or replace flaggers in these works zones; and (8) develop recommendations on the use of flaggers, spotters, and other safety measures in work zones with a posted speed limit greater than 40 mph on Illinois expressways and freeways. These recommendations can be used by IDOT to update and/or expand related IDOT policies, specifications, and standards in order to improve work zone safety and mobility. (Author/publisher)
Samenvatting