The AASHTO Manual for Assessing Safety Hardware (MASH) provides criteria for the full-scale crash testing and evaluation of roadside safety devices such as barriers, terminals, crash attenuators, breakaway structures, and longitudinal channelizers. The crash test matrices include requirements for vehicle type and mass and impact speed based on the desired test level. MASH additionally requires that a roadside hardware device be evaluated at its critical impact point (CIP) or critical impact angle (CIA), depending on the device category.  The CIP or CIA is defined as the point or angle that maximizes the potential for failure of the device based on structural loading, vehicle stability, vehicle snagging, or other considerations.

While MASH has specific guidance for the determination of CIPs for several types of barriers (such as post and beam longitudinal barriers) CIP guidance is much more general or nonexistent for many hardware systems. In these cases, MASH recommends that CIP determination be evaluated by computer simulation. However, not all test laboratories have computer simulation capabilities, and MASH recognizes that use of computer simulation solely for the purpose of determining CIPs is often not practical. Further, even if computer simulation is utilized for this purpose, MASH does not detail what factors to consider in the CIP analysis.

This lack of information regarding CIPs and CIAs leads to different interpretations by hardware developers and test laboratories, and results in inconsistency in crash testing that can influence the evaluation of devices in certain hardware categories. Research is needed to develop CIP and CIA guidance for implementation in MASH for device categories that have test matrices that include tests that lack specific guidance on CIP or CIA determination.

The objective of this research is to develop guidelines for selecting CIPs and CIAs in MASH tests for when criteria for CIP or CIA determination is undefined.