The objective of this project was to develop a guide for highway agencies to establish (a) priorities for upgrading existing safety hardware to standards in the Manual for Assessing Safety Hardware (MASH) 2016; and (b) policy on how such upgrading should occur.
Implicit in this discussion is the recognition that just because crash test procedures and evaluation criteria change does not mean that hardware developed using earlier criteria suddenly becomes unsafe. The process of improving roadside safety hardware is an incremental process where each generation of hardware is thought to be slightly more effective than the previous generation. Prioritizing upgrading policies involves assessing the incremental reduction in the risk of fatal and serious injury expected from upgrading roadside hardware and balancing that risk reduction with the highway agency costs of upgrading the hardware such that funds are expended to maximize overall network safety. Appreciating the underlying risk reductions and costs of upgrading are fundamental to developing effective upgrading policies.
The systematic data-driven process for roadside hardware replacement analysis described in this user’s guide is not meant to be prescriptive but informative. Engineers are likely to use this process as part of the decision-making process in combination with engineering judgment, agency experience, in-service performance history, and other highway agency objectives. The method presented herein is just one of several considerations that should be included in making roadside hardware replacement decisions. A highway agency may also consider ease of maintenance issues, stock-piling materials, project scheduling, contractor familiarity with various designs and other issues. The method presented herein, therefore is one facet of the decision-making process but should be used in conjunction with other considerations.
Status: Research is complete. The final report is available as a web-only document at https://www.nap.edu/catalog/26075/roadside-hardware-replacement-analysis-user-guide.