Fadi Tahan

Guidance for the Selection, Use, and Maintenance of Cable Barrier Systems

This report provides guidance for the selection, use, and maintenance of cable barrier systems. While cable barrier systems have been in use for more than 70 years, their use has been on the rise and is expected to continue in the future. The increase in use of cable barrier systems has been attributed to the success rate in keeping vehicles from crossing the median, reducing roadway departures, and decreasing impact severity. Due to advancements in cable barrier system technology, installation and repair costs are lower and cable barrier use has increased in varying roadway environments. Safety studies, although limited, have shown that cable barriers help reduce those median cross-over collisions that lead to some of the most severe head-on type crashes. This document will be of particular interest to design, maintenance, traffic, and safety engineering professionals.

Sensitivity Study of Jordan Rollover System and Unconstrained Model: Sensitivity at Varying Test Bed Mass and Yaw Angles

Finite element analysis was used to compare the dynamic rollover performance of a midsized sport utility vehicle with a strengthened roof in a Jordan Rollover System (JRS) test with an unconstrained rollover under the same initial conditions. The JRS can control closely the initial conditions of a vehicle being subjected to a rollover test. This research was proposed to study the ability of the JRS to emulate the vehicle kinematics and roof crush resulting from an actual rollover. An additional sensitivity study for the test bed mass and yaw angle was performed. The model was given initial conditions at impact similar to the JRS common values. These conditions were a roll angle of 145°, a pitch angle of 5°, a yaw angle of 10°, a test bed speed of 24 km/h, a vertical drop height of 10 cm, and a roll velocity of 190°/s. The finite element model of a 2003 Ford Explorer was used in this study and was validated against several full-scale tests. Then the roof was strengthened to meet the new federal roof regulation. Computer simulations comparing a JRS test with an unconstrained rollover showed that during a pure roof crush phase, both models behaved similarly. Afterward, some variations occurred, but the differences were less than 5%. For different test bed mass, the only significant difference between the model results was the final test bed speed. Finally, increasing the yaw angle in a JRS test showed a decrease in roll rate and intrusion characteristics of less than 5%.