Concept Development of a Bullnose Guardrail System for Median Applications
Description:... The research study consisted of the design, fabrication, and full-scale vehicle crash testing of a bullnose barrier concept for the end treatment of median hazards. The bullnose concept consisted of a 12-gauge thrie beam rail supported by twenty-two wood posts, eleven posts on each side of the system. Horizontal slots were cut in the valleys of selected thrie beam sections to aid in vehicle capture as well as to reduce the buckling and bending capacities of the rail. Two full-scale crash tests were performed, the first using a 2000-kg pickup truck and the second using an 820-kg small car. The first test, impacting at a speed of 101.4 km/h and an angle of 0.1 degrees at a 1/4-point offset, was unsuccessful. Although the vehicle showed no potential for vehicle override, the thrie beam ruptured causing uncontrolled penetration of the vehicle behind the barrier. Consequently, the bullnose system was modified to include additional breakaway posts and horizontal slots in other thrie beam sections. The second test, impacting at a speed of 103.3 km/h and an angle of 3.4 degrees was determined to be successful according to the safety standards set forth by the Test Level 3 evaluation criteria described in the National Cooperative Highway Research Program (NCHRP) Report No. 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features". The data and information gathered from the development phase of this project will be used in the development of a computer simulation LS-DYNA model of the bullnose system as well as an improved bullnose guardrail design
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