Exploration of road closure time characteristics of tunnel traffic accidents: A case study in Pennsylvania, USA

With the increase of roadway tunnels, tunnel traffic accidents are also increasing. Compared with open roadways, road closures caused by traffic accidents in the tunnel have greater influences on traffic operations, as tunnels are often the key junctions of the roadway network. With the traffic accident data of Pennsylvania from 1997 to 2020, this study is designed to identify the features and trends of road closure time due to tunnel traffic accidents. First, features of tunnel and non-tunnel traffic accidents are compared from the perspectives of accident consequences, environmental factors, risky driver behavior, and vehicle features. The data confirms that tunnel traffic accidents are more likely to lead to road closures than non-tunnel ones. Besides, tunnel traffic accidents are mainly consisted of rear-end and hit-fixed-object collisions with many speeding cases. Then, a Negative Binomial model is built to statistically identify the factors significantly influencing the road closure time, which is recorded as non-negative integer in the data. The estimation results indicate that collision type, accident severity, road type, driving under the influence, the involvement of heavy trucks, and the number of involved vehicles could significantly influence the road closure time, whereas lighting, road condition, speeding, and area are insignificant. Finally, based on the research findings, some countermeasures are proposed to reduce the road closure time caused by tunnel traffic accidents.