BACKGROUND

The American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) provides guidelines for crash testing roadside features and evaluation criteria to assess the test results. Using the philosophy of the “state of the possible,” the developers of MASH set lower occupant impact velocity (OIV) limits for sign and luminaire support structures and work zone devices than other roadside features because of the assumed relative ease in obtaining compliant test results for breakaway devices. The OIV limits are 4.9 m/s for all types of supports, whereas the limits for all other highway safety devices are 12.2 m/s. However, developing MASH-compliant devices in these families has proven difficult because of the conservative change in velocity requirements as well as occupant compartment deformation and penetration criteria. 

The current occupant risk criteria for these families of devices may preclude the use of energy-absorbing devices (e.g., poles, signs), which might ultimately be more conducive to favorable real-world crash outcomes in some applications. Energy-absorbing support structures are designed to decelerate a vehicle rather than allow it to break through with minimal speed reduction. Europe has developed a test standard to evaluate supports that uses the entire spectrum of support structures and occupant risk outcomes: EN12767, Passive safety of support structures for road equipment – Requirements and test methods. EN12767 accommodates the evaluation criteria in MASH but expands on possible outcomes based on the type of support structure, such as breakaway or energy-absorbing devices. 

Research is needed to collect available data on these types of devices and examine the test results with current U.S. and European Union (EU) standards to determine how concepts from the EU standards might be incorporated into MASH hardware evaluation.

OBJECTIVE

The objective of this project is to examine current U.S. and EU roadside safety hardware crash test criteria for sign and luminaire support structures and work zone devices and investigate how concepts from EU standards might be suitable for the United States.

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

TASKS

Task 1. Conduct a literature review of relevant research and other sources related to the project objective. The literature review shall include research on vehicle occupant risk as well as safety and crash testing for sign and luminaire support structures and work zone devices. The review shall include published and unpublished research conducted through the NCHRP; the Federal Highway Administration (FHWA); other national, international, and state organizations; and pooled fund studies.

Task 2. Review available in-service performance evaluations and comparable international evaluations of sign and luminaire support structures and work zone devices.

Task 3. Synthesize and summarize the results of Tasks 1 and 2. Define the knowledge gaps relevant to the project objective. Document the findings of Tasks 1 through 3 in a technical memorandum.

Task 4. Develop a method to achieve the project objective to be executed in Phase II. For sign and luminaire support structures and work zone devices, the method shall, at a minimum, formulate strategies to:

• Analyze the differences between current U.S. and EU crash test procedures and evaluation criteria, including but not limited to factors such as vehicle types, centers of gravity, vehicle occupant risk, and vehicle behavior post impact;
• Develop a list of device families (e.g., single or multiple sign support structures, longitudinal channelizers, energy-absorbing luminaire supports) applicable to the project objective;
• Develop criteria for ranking device families for study;
• Rank and recommend device families;
• For the selected device family(ies);
  • Investigate current occupant risk criteria threshold(s) related to injury risk in the context of crash testing;
  • Analyze selected U.S. and EU crash tests; and
  • Explore how concepts from EN12767 or other applicable EU standards can inform updates to MASH, including different evaluation criteria for different families.

Task 5. Prepare Interim Report No. 1, which documents Tasks 1 through 4 and provides an updated work plan for the remainder of the research.

PHASE II – Method Development

Task 6. Execute the method in the approved Interim Report No. 1. Summarize the findings in a technical memorandum and participate in a virtual meeting to debrief the NCHRP panel.

Task 7. Prepare a stand-alone document with MASH language for AASHTO consideration and other supporting materials (hereafter called AASHTO deliverables) based on the research results. This resulting language may be considered by AASHTO for the next MASH updates. 

Task 8. Develop an outreach plan to gather feedback on the findings of Tasks 6 and 7, including at least two workshops (either virtual or in-person) both hosted by the contractor with attendees representing diverse viewpoints, including testing laboratories, industry, international participants with experience with EU standards, and state departments of transportation (DOTs). The workshops will be executed in Phase III. Prepare draft materials and attendee list.

Task 9. Prepare Interim Report No. 2, which documents the results of Tasks 6 through 8 and provides an updated work plan for the remainder of the project.

PHASE III – Final Deliverables

Task 10. Execute the outreach plan per the approved Interim Report No. 2. Summarize the activities and findings in a technical memorandum.

Task 11. Revise the AASHTO deliverables based on the findings of Task 10 as approved by the NCHRP. The AASHTO deliverables are due at least 6 months before the contract end date.

Task 12. Prepare the final deliverables, including:

• A research report, including an executive summary, documenting all research, findings, and project efforts;
• The AASHTO deliverables;
• A PowerPoint presentation with speaker notes summarizing the project and distinctly illustrating for the audience how the research can be applied in their organization; and
• A technical memorandum titled “Implementation of Research Findings and Products”.

STATUS: Proposals have been received in response to the RFP. The project panel will meet to select a contractor to perform the work.