The National Academies

NCHRP 03-134 [Final]

Determination of Encroachment Conditions in Work Zones

  Project Data
Funds: $428,073
Research Agency: Texas A&M Transportation Institute
Principal Investigator: Chiara Dobrovolny
Effective Date: 6/20/2019
Completion Date: 11/30/2022
Comments: Published as NCHRP Research Report 1055

There were 96,626 crashes in roadway work zones in 2015. This equates to one work zone crash every 5.4 minutes. Every day, 70 work zone crashes result in at least one injury, and every week, 12 work zone crashes result in at least one fatality. Previous research regarding work zone encroachments indicates that there is a higher frequency of fatalities in work zone crashes than nonwork zone crashes (National Work Zone Clearinghouse). Thus, work zones may be an area where significant safety improvements can be made.
While current data suggest that work zones have a higher risk for crashes and fatal injuries, data on the impact conditions associated with work zone crashes is poorly documented. More data is needed to identify areas for improvement in the design of work zones and the safety barriers used therein to improve safety in work zones for the traveling public and highway workers. If encroachments for work zones are different than nonwork zones, designers will be able to balance the use of temporary features and optimize the use of public funds by using less expensive barriers.  This research is needed to support updates to the Manual for Assessing Safety Hardware (MASH), the Roadside Design Guide (RDG), and the Manual for Uniform Traffic Control Devices (MUTCD).
The objective of this research was to evaluate work zone encroachments and develop guidance to improve safety for workers and the traveling public in roadway work zones. The guidance addresses all aspects of work zones from planning (including when to use positive protection) through implementation, and be useable by any entity involved in the life cycle of the work zone.
The research addressed areas of interest related to work zone encroachments and safety on all roadway types, such as, but not limited to, the following:  
  • Review and define encroachment conditions in work zones;
  • Review methods to collect encroachment data in work zones;
  • Develop a data collection plan for work zone encroachments;
  • Collect and evaluate work zone encroachment data;
  • Analyze driver behavior in work zone encroachments;
  • Review state work zone management practices;
  • Assess the applicability of MASH guidance for work zone application and propose modifications;
  • Based on the results, develop methods to improve the collection of encroachment data;
  • Develop guidance to address encroachments and improve safety in work zones; and
  • Develop methods to validate the safety and effectiveness of the guidance.
Status:  Completed. The final report is available here: https://www.trb.org/Publications/Blurbs/183017.aspx 

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