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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation
FHWA Highway Safety Programs

Reduce Crash Severity

Hardware, such as barriers, sign supports, and work zone devices are commonly used to reduce the potential severity of crashes on the roadside. Crash testing is used to evaluate the crashworthiness of these devices.

The American Association of State Highway Transportation Officials (AASHTO) provides guidance related to the design and installation specifications of roadside hardware and safety hardware. The FHWA's Federal-aid eligibility letters are provided as a service to the States and are not a requirement for roadside safety hardware to be eligible for Federal-aid reimbursement. As stated in our eligibility letters, "eligibility for reimbursement under the Federal-aid highway program does not establish approval, certification or endorsement of the device for any particular purpose or use." Decisions regarding the purchase and use of roadside safety hardware devices are the responsibility of the transportation facility owner.

Understanding the performance of roadside safety hardware begins in a controlled, sterile laboratory environment using crash test scenarios and standards set and maintained via AASHTO's Manual on Assessing Safety Hardware (MASH). However, laboratory tests cannot completely protect against all the variables and countless situations drivers may find themselves in. Therefore, FHWA encourages states to perform in-service performance evaluations to identify real world performance of hardware so all stakeholders have a more comprehensive understanding of these devices' performance. For more information about in-service performance evaluation of roadside safety devices, please visit

Hardware Eligibility Letters

Guidance and Policies