Design Approach for Improving Current Concrete Median Barriers on Highways in South Korea

The speed of vehicles on highways has increased due to improved driving environments. However, this increased speed has become one of the main reasons for collisions between vehicles and road barriers. Several fatalities have occurred recently in South Korea as a result of fragmentation due to the collision of a vehicle with a concrete median barrier. The current impact level of a concrete median barrier (CMB) is SB5-B (270 kJ). However, the impact level of the collision was estimated to be over SB7 (2,300 kJ). Inspired by this, many engineers agree on the use of improved CMBs to reduce the amount of concrete fragmentations due to vehicle impact. In the present study, several designs of CMBs have been presented and a numerical analysis was conducted to evaluate the impact resistance of CMBs against vehicle impact loadings. A new impact severity [SB5-B(20A)] was also proposed. Firstly, commercially available wire-mesh reinforcements and an increase in cross section were considered as design modifications under the proposed impact severity. In addition to this, a novel CMB, the High CMB (Hi-CMB) has also been introduced in this paper which has several shock absorbers without incurring any increase in construction cost. The newly developed Hi-CMB was evaluated by the developed collision model. It was found that the Hi-CMB with shock absorbers can reduce concrete fragmentation by 99% compared to the current type of CMB in South Korea. Shock absorbers generally activated and increased the impact resistance especially at high impact levels. As a result, an enhanced impact resistance, due to the addition of reinforcement, section expansion, and shock absorbers was obtained under SB5-B(20A). The mixed effects of those design modifications led to an effective design of CMBs against the impact loadings of heavy trucks.