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1  The lateral extension of vehicle components behind, above, or below the front face of a traffic barrier is referred to as zone of intrusion, or ZOI. A literature review was conducted on previous ZOI research, full-scale crash testing, and simulation studies for various rigid traffic barriers. This review included 95 successful crash tests conducted according to AASHTOâs Manual for Assessing Safety Hardware (MASH), 2nd ed. (AASHTO 2016) test levels (TL) 2 through 5 and NCHRP Report 350 (Ross et al. 1993) TL-5. For the purposes of this study, a barrier was considered rigid if the dynamic deflection was less than or equal to 10 in. during impact. Barrier profiles considered included New Jersey, F-shape, single-slope, vertical, and low-profile concrete barriers as well as steel bridge rails and steel-concrete combination rails. During evaluation, similar barrier shapes were grouped together for ZOI envelope development. Eighty of the 95 tested barriers deflected less than 10 in. and were therefore considered rigid; of these, 47 had enough publicly available video and data to obtain ZOI measurements. Simulation studies were also evaluated for modeling parameters that could be used to optimize vehicle-to-barrier interactions for calibration and investigation purposes. Based on the available data, however, no clear trends were observed between barrier profile and ZOI envelope estimated from test data. A survey of state DOTs was conducted to determine which states utilized ZOIs in road- side barrier design standards and to evaluate the typical heights of rigid roadside barriers. Thirty-one state DOTs completed an agency survey to gather information on barrier shapes and heights used at each MASH test level. Many state DOTs used ZOI criteria if necessary to place a fixed object adjacent to a barrier but avoided this placement when possible. Single- slope barriers were most common across all test levels; various barrier heights were used at each test level, many exceeding the minimum requirement. LS-DYNA simulations using existing vehicle models were used to fill gaps in existing crash test data to develop final MASH ZOI envelopes. To improve model stability, minor modifications were made to an existing RAM pickup truck, single-unit truck (SUT), and tractor-trailer models. Although major updates were beyond the scope of this project, the implemented modifications improved model calibration by correlating more closely with some extremes of test data. Calibrated vehicle models were used to estimate ZOI envelope boundaries using barrier configurations commonly used by state DOTs, especially barrier heights near the maximum at each test level. Vertical, 10.8-degree single-slope and F-shape barriers were considered. MASH TL-2 simulations were conducted on barriers ranging from 24 to 54 in. tall. MASH TL-3 simulations were conducted on barriers ranging from 29 to 54 in. tall. MASH TL-4 S U M M A R Y Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments
2 Zone of Intrusion Envelopes Under MASH Impact Conditions for Rigid Barrier Attachments simulations were conducted on barriers ranging from 36 to 90 in. tall. Finally, MASH TL-5 simulations were conducted on barriers ranging from 42 to 90 in. tall (AASHTO 2016). Data collected from rigid barrier crash tests and simulations were compiled to form ZOI envelopes and compared to the crash test data used to develop ZOI envelopes in the AASHTO Roadside Design Guide (RDG) (AASHTO 2011). Based on trends observed in the relation- ship between barrier height and ZOI maximum width, a series of ZOI envelopes were created that best captured maximum practical results from simulations and full-scale testing. The ZOI envelope recommendations shown in Chapter 6 are recommended to update the RDG.
