Safety Analysis of Freeway Interchanges

While investigating Jingjintang Expressway's traffic accidents, it is clear that, crash frequency and rates at interchange areas are more severe than that at other locations. To further explore the relationship between crash rates and characteristics of freeway geometric design features, this study analyzed the existing safety problems at Jingjintang Expressway's interchanges. Particularly we examined crash characteristics at ramps including length of acceleration lanes and deceleration lanes, ramp geometric design, traffic control devices at ramps and locations of toll plazas. The driver behavior and performance of overloaded trucks on ramps were also studied. The results of the study have clearly shown that it is important to have a uniform traffic information system and a consistent traffic control system. Most importantly, the study has concluded that the length requirements in our current design specification for ramp acceleration and decoration lanes are not sufficient for safety, particularly for large vehicles. A set of recommendations are made as a result of this study.