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Concept Design and Analysis of Nebraska Turned-Down Approach Terminal Sections


TRP-03-045-95 (Turndown)


Gene Paulsen, John Reid, Ronald Faller, Dean Sicking




Turned-down terminal sections were analyzed using LS-DYNA3D, a finite element modelling package with capabilities for simulating vehicular impacts into roadside hazards. A baseline simulation was conducted on the existing turned-down approach terminal section, as well as on various retrofit options. The simulation package was used to select the two most promising options. Six low speed bogie tests, and one high speed bogie test were conducted on the modified Nebraska Turned-Down Approach Terminal Sections. All tests were conducted with a 1979 Honda Civic with a gross static weight of 885-kg (1945-lb). Impact conditions were at 0 degrees with a 36-cm (15-in.) offset toward the roadway. The low-speed tests were conducted at 16 kph (10 mph), and the high-speed test was conducted at 96 kph (59.5). The high-speed test was conducted and reported in accordance with the requirements specified in the Recommended Procedures for the Safety Performance Evaluation of Highway Appurtenances, National Cooperative Highway Research Program (NCHRP) Report No. 230. The safety performance of the modified Nebraska Turned-Down Approach Terminal Section was determined to be unacceptable according to the NCHRP 230 criteria. However, the desired behavior of the turned-down section was achieved. It is believed, that revising the post installation procedures could create a terminal section that would perform satisfactorily.


Highway Safety, Roadside Safety, Roadside Appurtenances, Terminal, Turn-down, Computer simulation, NCHRP-230, LS-DYNA, Bogie Test,

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