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Development of Iowa DOT Combination Bridge Separation Barrier with Bicycle Railing - Phase I




Bob Bielenberg, Chaz Ginger, Cody Stolle, John Reid, Ronald Faller, Scott Rosenbaugh




Iowa Department of Transportation (Iowa DOT) typically builds separation barriers between vehicle and pedestrian/bicycle facilities when sidewalks or trails are present on vehicular bridges. Currently, Iowa DOT employs a combination bridge rail that utilizes a concrete parapet that had previously been successfully evaluated to National Cooperative Highway Research Program (NCHRP) Report No. 350 Test Level 4 (TL-4) criteria for these situations. While the parapet had been successfully evaluated, the combination bridge rail system as a whole had not been evaluated to any crash test standards. Iowa DOT desired that researchers at Midwest Roadside Safety Facility (MwRSF) design and test a combination bridge separation barrier to current Manual for Assessing Safety Hardware, Second Edition (MASH 2016) TL-2 standards to use in place of their current, untested system. During this effort, previous combination rails, low-height vertical parapets, and zone of intrusion (ZOI) studies were reviewed to provide guidance on system design. A simulation effort was also performed to aid in height selection of the parapet, as well as placement of the attached bicycle rail to reduce the amount of negative vehicle-to-rail interaction with the system. Using the gathered data, a full system design was produced. It was then recommended that the proposed system be evaluated to MASH 2016 test designation no. 2-11 in order to assess the system’s performance during a vehicle impact scenario.


Highway Safety, Roadside Appurtenances, MASH 2016, Simulation, LS-DYNA, LRFD, Bicycle Rail, TL-2

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