Background: NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features,"
which was published in 1993, is the latest in a series of documents aimed at providing guidance on testing and evaluating roadside safety features. It incorporated significant changes and additions to procedures for safety-performance evaluation, including criteria for multiple performance levels, translation to metric units, and updates reflecting the changing character of the highway network and the vehicles using it. Subsequently, the Federal Highway Administration (FHWA) adopted the document as policy through the federal rulemaking process.
NCHRP Project 22-14, "Improvement of Procedures for the Safety-Performance Evaluation of Roadside Features," was initiated to identify the need for changes to the content of NCHRP Report 350.
Since publication of Report
350, changes have occurred in vehicle fleet characteristics, testing technology, other specifications, and the literature on related research. Project 22-14 was intended to address several of the highest priority topics or issues that should be contained in the update. Topics that were addressed are:
- Test vehicles and specifications,
- Impact conditions,
- Critical impact point,
- Efficacy of flair space model,
- Soil type/condition,
- Test documentation, and
- Working width measurement.
Project 22-14 conducted a background analysis to determine the need for changes (e.g., review of changes in the fleet from sales data); recommended specific proposed changes or additions to the procedures for safety performance evaluation; and performed an assessment of the expected effects that may be associated with the recommended changes or additions. The efforts under Project 22-14 provide a substantial amount of the material needed to rewrite the procedures, but not all topics or issues have been addressed. For example, a reassessment of the 820C and 2000P test vehicles is needed because of changes in the vehicle fleet and lack of available test vehicles. Several other issues that were not addressed pertain to the subjectivity of some of the evaluation criteria. For example, occupant compartment intrusion is a criterion that is not objectively defined by Report 350
and was not addressed by Project 22-14. Additional research is needed for unresolved topics and issues to be addressed and integrated into a single document.
Before the publication of Report 350,
no crash testing and only limited analytical evaluation were performed to determine the consequences of the changes in the criteria, i.e., the ability of existing hardware to pass the new tests. All future changes need to be evaluated, before consideration for adoption by AASHTO, to determine the effect of the new criteria on existing hardware.
The objectives of this research are to prepare improved procedures for the safety-performance evaluation of roadside features and identify research needs for future improvements to the procedures.
Accomplishment of the project objectives will require at least the following tasks. (1
.) Conduct a brief review and reassessment of the 7 issues addressed in NCHRP Project 22-14. ( 2.
) Review other relevant literature and ongoing research and conduct a survey to identify additional needs that were not addressed in the final report for Project 22-14. (3.
) Identify potential revisions to the procedures. (4.
) Develop a test plan for assessing the crash test performance of existing roadside safety devices when subjected to the new procedures proposed in Task 3. The test plan shall consider, but is not limited to, crash testing and finite element analysis. (5.
) Submit an interim report documenting the findings from Tasks 1 through 4. The report, as a minimum, shall include the following:
- Summary and prioritization of information needed to update Report 350,
- Test plan developed in Task 4,
- Estimated costs and time, and
- Future research needs.
) Meet in Washington, D.C., with the NCHRP panel to review the Task 5 interim report, including the test plan, approximately 1 month after its submittal. Submit a revised interim report reflecting the panel's review comments. ( 7.
) Execute the approved test plan. (8.
) Submit for NCHRP review a preliminary draft final report documenting the entire research effort including an appendix, suitable for adoption and publication by AASHTO, containing the recommended procedures. (9.
) Revise the preliminary report based on the project panel's recommendations. (10.
) Submit the revised report to an AASHTO task group for review. Summarize the comments from the task group review and make recommendations to the panel for revision of the report. Incorporate the approved recommendations into the procedures. (11.
) Prepare a final report documenting the entire research effort including an appendix containing the recommended procedures.
The project has been completed and the revised crash test procedures published by AASHTO.
Product Availability: AASHTO publication, "Manual for Assessing Safety Hardware (MASH)"