Tl 4 Crash Testing Of The F411 Bridge Rail
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TL-4 Crash Testing of the F411 Bridge Rail
Texas Department of Transportation (TXDOT) and Florida Department of Transportation (FDOT) frequently receive requests to provide aesthetically pleasing traffic rails for use on select bridges and roadways. TxDOT, in response to providing context sensitive design alternatives, initiated a project to develop additional aesthetically pleasing rail alternatives. Under a previous TxDOT project, the F411 bridge rail was constructed and crash tested to Test Level 3 (TL-3). The TL-3 test is a 4405-lb (2000 kg) pickup impacting the railing at 25 degrees and 62.2 mi/h (100 krn/h). This test requires both containment and stability, and non-overturning. Since some breakage of the parapet is possible, potential for vehicle snagging is likely. Vehicle snagging can contribute to vehicle instabilities in the redirection sequence and potential rollover. The TxDOT F411 bridge rail contained and redirected the vehicle, which remained upright during and after the collision period. The bridge rail met the required specifications for NCHRP Report 350 test 3-11. The objective of this research is the full-scale crash test and evaluation of the F411 to Test Level 4 (TL-4). The most direct approach for accomplishing the objectives of this task is to perform a full-scale TL-4 crash test of this railing design. The TL-4 vehicle is a single-unit box-van truck impacting the railing at 15 degrees and 49.7 mi/h (80 krn/h). While containment is required, overturning of the vehicle 90 degrees is an acceptable test outcome. The TxDOT F411 bridge rail performed acceptably for NCHRP Report 350 test 4-12. Based on the performance of the F411 bridge rail in the full-scale crash test to TL-4 test conditions, the F411 may be used where containment of 18,000 lb single-unit trucks is desired.
Crash Testing and Evaluation of the Modified T77 Bridge Rail
Under a previous study, Texas Transportation Institute (TTI) and the Texas Department of Transportation (TxDOT) worked cooperatively to conceptualize and develop two aesthetically pleasing and crashworthy rail designs. The rails were designated the T77 and F411. Researchers performed and evaluated full-scale crash tests on the new rails in accordance with National Cooperative Highway Research Program (NCHRP) Report 350 test 3-11. The TxDOT F411 bridge rail performed acceptably according to the evaluation criteria of NCHRP Report 350. However, the T77 design failed to perform acceptably with the pickup truck. The objective of this project was to modify the TxDOT T77 bridge rail to perform as an aesthetically pleasing and crashworthy bridge rail. TTI and TxDOT worked cooperatively to modify the design to make the rail perform satisfactorily. Researchers performed full-scale crash tests in accordance with NCHRP Report 350. The T77 bridge rail was modified so it would perform in accordance with the evaluation criteria for NCHRP Report 350 test 3-11.
Vehicular Crash Tests of the California ST-20 Bridge Rail
Over the course of this project a see-through steel bridge rail (Type California ST-20) was developed and tested. The ST-20, as tested, is at the limits of meeting the NCHRP Report 3501 TL-4 test matrix. The bridge rail also met the requirements established in the AASHTO Bridge Design Specifications for use as a bicycle rail and is considered an aesthetically pleasing see-through bridge rail. The barrier, as tested, uses steel posts at 3-m spacing to support four boxbeam rails and one additional handrail to meet the height requirements for bicycles. Because the ST-20 is based on a TL-4 bridge rail from Wyoming DOT3,4, only Test 4-11 (NCHRP Report 350) was considered necessary.