BACKGROUND

Historically, the safety performance of roadside safety hardware has been evaluated through full-scale vehicular crash testing, which is notably expensive and time-consuming. Additional physical crash testing may be required to approve roadside safety device modifications. Recently, certain types of finite element analysis (FEA) crash simulations have been tested and used for the approval of design modifications. Many transportation agencies are now considering the acceptance of computer simulation in lieu of full-scale crash tests to approve modifications to roadside safety hardware. The transition to computer simulation has enabled design optimization and substantially reduced the need for expensive and lengthy physical crash tests, thereby decreasing the overall development and installation costs of roadside safety hardware.

NCHRP Web-Only Document 179: Procedures for Verification and Validation of Computer Simulations Used for Roadside Safety Applications (2011) established the first standardized verification and validation (V&V) procedure for roadside safety hardware in the United States. These procedures were developed based on the requirements outlined in the NCHRP Report 350: Recommended Procedures for the Safety Performance Evaluation of Highway Features. However, in 2009, the Manual for Assessing Safety Hardware (MASH) superseded the NCHRP Report 350, emerging as the latest roadside hardware crash testing standard.

While the previous NCHRP document provided unified simulation comparisons for the rigid vertical-faced barrier, research is needed to update the V&V procedures for the broader spectrum of roadside safety hardware according to the categories and test levels specified in MASH. The revised V&V procedure is expected to enable end users, such as state departments of transportation (DOTs), to use computer simulations (e.g., FEA) as a viable alternative to full-scale crash testing for MASH hardware review and approval. In addition, there is a need to standardize the simulation reporting format beyond the V&V process to enable state DOTs to conduct more effective and consistent reviews of crash simulation testing results.

 OBJECTIVE

The objective of this research is to develop guidelines to establish two key elements: (1) a standardized, confidence-level-based procedure for the V&V of computer simulations of roadside safety hardware, applicable across all MASH categories and test levels; and (2) a uniform reporting format for computer simulation inputs and results to facilitate consistent comparison and review.

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

TASKS

PHASE I – Preliminary Research

Task 1a. Conduct a comprehensive literature review on existing guidelines and research for V&V practices. The review shall include published and unpublished research conducted through the NCHRP; the Federal Highway Administration (FHWA); the American Association of State Highway and Transportation Officials (AASHTO); other national, state, and local agencies; and international organizations to identify foundational elements for the research.

Task 1b. Engage with a broad spectrum of stakeholders through surveys, interviews, and focus groups. This is to determine what V&V procedures are utilized, who benefits from the standardized simulation results, and how DOTs could incorporate computer simulation in roadside hardware testings. Additionally, identify what information and reporting formats are most effective for DOTs to review and compare V&V assessment results for roadside hardware. 

Task 1c. Perform an extensive search for data encompassing all MASH categories and test levels, which could be utilized in the V&V process. Document both the data availability and the specific data needs for the V&V process.

Task 2. Evaluate and synthesize the findings from Task 1 to identify knowledge gaps related to the project objective. These gaps shall be addressed in the final product or the recommended future research as the budget permits.

Task 3. Develop a research methodology to accomplish the project objective. The methodology shall, at a minimum, include the following:

• A comprehensive V&V procedure, including how to determine the confidence level in using computer simulation for crash testing of roadside devices;
• Factors that may affect the confidence level of simulation results;
• Updated V&V evaluation criteria to meet the new requirements listed in the MASH;
• Comparison thresholds for other impacts beyond oblique and rigid barrier full-scale impacts;
• Criteria for validation against multiple crash tests on the same system;
• The need for multilevel validation of various components of the system;
• The limitations of models;
• Criteria for comparing occupant compartment deformation;
• A standardized reporting format to ensure the uniformity of necessary information and format for simulation results; and
• Future research needs, including a roadmap for FHWA and state DOTs to evaluate, review, and approve simulation results as an alternative to full-scale crash testing when feasible, as well as additional requirements specific to electric vehicles.

Task 4. Identify the requirements and functionalities of a standalone tool to support the V&V procedures.

Task 5. Develop an annotated outline for the guidelines, and propose a schedule for the development of the guidelines with four submission and review stages. The outline is intended to provide the foundation, context, and framework for the draft guidelines to be developed in Task 7.

Task 6. Prepare Interim Report No. 1 that documents Tasks 1 through 5 and provides an updated and refined work plan for the remainder of the research. The updated plan must describe the process and rationale for the work proposed for Phase II.

PHASE II – Execution 

Task 7. Execute the methodology as outlined in the approved Interim Report No. 1. The draft guidelines shall be provided to the NCHRP no later than 18 months after the contract execution.

Task 8. Develop a tool to support the V&V procedures to evaluate, review, and approve roadside hardware based on computer simulation as an alternative to crash tests.

Task 9. Apply the draft guidelines to at least three crash simulations of different MASH hardware types. Revise the draft guidelines and roadmap as appropriate. The results shall be provided to the NCHRP no later than 21 months after the contract execution. The NCHRP shall approve the selected crash simulations first.

Task 10. Present the draft guidelines and roadmap to appropriate AASHTO committees for comments and propose any revisions to the NCHRP. The research team shall anticipate making two in-person presentations during the research to the AASHTO Technical Committee on Roadside Safety and to the AASHTO Committee on Design. Revise the draft guidelines and roadmap after consideration of review comments.

Task 11. Prepare the final deliverables, which at a minimum shall include the following:

• Guidelines for V&V procedures and a research report that documents the entire research efforts;
• A standardized V&V reporting form(s);
• A standardized format of the simulation inputs and results;
• A standalone tool to support V&V procedures;
• A roadmap for using simulation results as an alternative to full-scale crash testing;
• Other media and communication material (presentation, video clips, graphics, press releases) to support the project findings; and
• A stand-alone technical memorandum titled “Implementation of Research Findings and Products.”

STATUS: A research contractor has been selected for the project.  The contracting process is underway.