The National Academies

NCHRP 22-28 [Active]

Criteria for Restoration of Longitudinal Barriers, Phase II

  Project Data
Funds: $300,000
Staff Responsibility: Mark S. Bush
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 is 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. It is expected that this research will continue the work begun under NCHRP Project 22-23 and may involve a combination of component testing, pendulum testing, and computer simulation. Full-scale crash testing may be considered to validate the other methods of analysis, but is not the focus of this research.

Accomplishment of the project objective will require at least the following tasks.


(1). Review the work undertaken in NCHRP Project 22-23, as well as recently completed and ongoing relevant research. Survey the state and provincial transportation agencies to determine their plans for implementing NCHRP Report 656 and to identify damage modes and other system elements (e.g., wood posts, transitions, end treatments) that should be added to those covered by the report. Augment the survey results with input from the AASHTO Technical Committee on Roadside Safety, TRB Standing Committee AFB20, AASHTO/AGC/ARTBA Task Force 13, and the ATSSA Guardrail Committee. (2). For each damage mode and system element identified in Task 1, analyze the importance of addressing it and the research methods that could be used for evaluation. Prioritize the damage modes and system elements for inclusion in the research plan to be carried out in Task 4. (3). Within 4 months of contract execution, prepare an interim report summarizing the work performed in Tasks 1 and 2 and recommending a research plan to qualitatively and quantitatively assess the highest-priority damage modes and system elements described in Task 2. The plan should describe and estimate costs for analyses, supporting tests, and validation tests that will be used to develop metrics for assessing the operational performance of a damaged barrier (per NCHRP Report 350, Test Level 3). The research plan should provide options totalling approximately 150% of the budget for Task 4; the excess is intended to give the project oversight panel discretion in selecting the research to be conducted. The interim report should also include a preliminary outline for additions to Chapter 16, "A Field Guide for the Restoration of Longitudinal Barriers," of NCHRP Report 656. (4). Execute the research plan for assessing damage modes and system elements as approved by the panel at the interim meeting. (5). Develop additional material for the field guide for the damage modes and system elements addressed in Task 4. The material should be consistent with Chapter 16 of NCHRP Report 656. (6). Field-test and fine-tune the field guide material developed under this project with maintenance personnel from at least one state DOT approved by the panel. (7). Prepare a field guide combining Chapter 16 of NCHRP Report 656 and the additional material from Tasks 5 and 6. (8). Submit a final report documenting the entire research effort, describing future research efforts (e.g., additional damage modes, further validation of the field guide), and including the Task 7 field guide as a stand-alone appendix. The field guide should also be provided as an independent electronic document suitable for downloading and printing by transportation agencies.

STATUS: Completed--Final Report sent to AASHTO.

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