Reduced Impact Angles with Temporary Barriers in Work Zones

Positive protection (i.e., temporary construction barriers) are used in work zones to separate construction workers from adjacent traffic. When temporary barriers are impacted by an errant vehicle, they will deflect a few inches up to several feet into the work area. At the same time, providing a non-work area behind temporary barrier further constricts the already limited work area. Devices placed in work zones, such as temporary barriers, must be full-scale crash tested to the same criteria—typically 25-degree impact angles and 62 mph impact speeds—as other roadside devices based on the AASHTO Manual for Assessing Safety Hardware (MASH) or similar test criteria. However, lanes are often narrower in work zones, reducing the potential encroachment angle. Additionally, work zones are by nature temporary, so the exposure and overall potential for an errant vehicle to impact a work zone device is much less than permanent roadside devices. Several agencies, including Caltrans, Virginia Department of Transportation (DOT), North Carolina DOT, and Pennsylvania DOT, make allowances for assuming reduced impact angles at different levels of application. A more scientific approach is needed to understand benefits, costs, and potential crash scenarios. The research objective is to develop temporary barrier warrants, placement guidelines, and associated barrier deflection characteristics to optimize work zone designs, specifically using reduced impact angles, for road user and worker safety. These guidelines may include designing temporary barrier in work zones where shallower angle vehicle impacts or lower impact speeds may occur and criteria for consideration such as number of lanes, lane widths, speed, traffic volume, and work zone layout. The research should evaluate temporary concrete barriers with flexible connections, pin and loop types of connection, and moment bearing connections, like an “X-Bolt” type of connection. Additionally, varying barrier lengths should be evaluated to determine the contribution of length to barrier deflection. The results of NCHRP Project 03-134, “Determination of Encroachment Conditions in Work Zones” should be reviewed and incorporated as necessary. Computer programs will be used to perform this research. Results of earlier full-scale crash tests can be used to validate simulations performed for this proposed research. This will allow for use of parametric studies of varying impact conditions for the simulations to establish criteria for implementation.


  • English


  • Status: Proposed
  • Funding: $400000
  • Contract Numbers:

    Project 22-62

  • Sponsor Organizations:

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Project Managers:

    Turner, Anne-Marie

  • Start Date: 20230725
  • Expected Completion Date: 0
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01888642
  • Record Type: Research project
  • Source Agency: Transportation Research Board
  • Contract Numbers: Project 22-62
  • Files: TRB, RIP
  • Created Date: Jul 25 2023 8:24AM