This report summarizes the research efforts of using finite element modeling and simulations to evaluate the performance of generic low-tension cable median barriers (CMBs) on four-lane and six-lane freeways with a 46-foot median, horizontal curvature, and 6:1 and 4:1 median slopes. A literature review is included on the performance evaluation of CMBs and applications of finite element modeling and simulations in roadside safety research. The modeling and simulation work is presented on a CMB with vehicular impacts of a 1996 Dodge Neon and a 2006 Ford F250 at 62.1 mph (100 km/hr). The placement of CMB at 4, 6, and 8 ft (1.22, 1.83, and 2.44 m) from the median centerline was evaluated under vehicular impacts at three departure angles (20, 25, and 30 degrees).
The simulation results show that the current NCDOT CMB meets the Test Level 3 (TL-3) requirements of MASH when placed at 4 ft (1.22 m) from the median centerline on the 6:1 slope of a four-lane freeway. The backside impacts to the CMB placed at 8 ft (2.44 m) from the median centerline on the 6:1 slope of a four-lane freeway only partially engages the vehicle, which allows the vehicle to enter the opposing travel lane before being redirected or stopped.
Compared to the CMB on a four-lane freeway, the CMB placement at 8 ft (2.44 m) from the median centerline on a six-lane freeway has reduced performance in both the front-side and backside impacts by the Ford F250 for TL-3 requirements of MASH. For the tested impacts with a Dodge Neon, the CMB on the 6:1 slope of the six-lane freeway has similar performance to that of a four-lane freeway on the 6:1 slope.
Based on the simulation results, placing the CMB at 6 ft (1.83 m) from the median centerline on a 4:1 slope of a six-lane freeway is not recommended.
