Safety Design of Median Barriers Impacted on Elevated Road

Most median barriers on urban elevated road are often adopted concrete blocks. The blocks are laid on the elevated road surface only by deadweight. As they are in defect of sustentation and concatenation, the blocks are probably exculpated, overturned or shifted when vehicle collision accidents occurred. The vehicle out of control may crash the median barriers and enter the opposite lanes, blocking bidirectional lanes. At the same time, the motion state of the vehicle will suddenly change, like whipping, rebounding and obtaining bigger acceleration, which will lead to traffic accident. Such barriers not only lose the function of protect vehicles and lead to traffic crash. Based on LS-DYNA calculating platform, the paper established car-barriers collision model and designed a new type of median barrier model with joints between concrete blocks, which is safer and has effective protection function. The simulating results indicate that the new barriers can still protect the traffic safety under the condition that the mass of car is 2 t, the impact velocity is 60 km/h and the impingement angle is 20deg, and the traffic safety of urban elevated road is improved.