The National Academies

NCHRP 22-28 [Final]

Criteria for Restoration of Longitudinal Barriers, Phase II

  Project Data
Funds: $300,000
Research Agency: RoadSafe, LLC
Principal Investigator: Malcolm Ray
Effective Date: 1/2/2012
Completion Date: 6/30/2015

NCHRP Project 22-23, “Criteria for the Restoration of Longitudinal Barriers,” researchers surveyed the states to determine what, if any, formal guidelines they have for the maintenance of guardrails. The research determined that while some states did have guidelines for evaluating existing guardrails to determine whether maintenance was warranted, these guidelines were typically based on judgment and were not supported by underlying research. NCHRP Report 656: Criteria for Restoration of Longitudinal Barriers (a product of Project 22-23) provides guidance to assist maintenance personnel in identifying levels of damage and deterioration to longitudinal barriers that affect operational performance. The researchers evaluated 11 damage modes (including damage due to crashes, environmental deterioration, and other causes) commonly associated with the standard strong steel post W-beam (modified G41S) guardrail; they evaluated these modes through a combination of component testing, pendulum testing, finite element simulation, and full-scale crashtesting. The report includes recommendations for additional research to address additional damage modes for barriers. Similar maintenance guidelines for cable barriers are publicized in NCHRP Report 711, Guidance for the Selection, Use, and Maintenance of Cable Barrier Systems, a product of NCHRP Project 22-25, "Development of Guidance for the Selection, Use, and Maintenance of Cable Barrier Systems.” 

The objective of this research was to develop more comprehensive guidance to assist maintenance personnel in determining the extent of damage to semi-rigid longitudinal barriers that affects operational performance. The guidance may cover additional strong steel post W-beam guardrail failure modes or other types of longitudinal barriers. 

Research complete. The final report is available as NCHRP Web-only Document #304 at https://www.trb.org/main/blurbs/182506.aspx

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