Traffic Characteristics for Long-Term Use of Emergency Lane: An Exploratory Field Test on G42 Freeway in China

Emergency lanes on motorways are designed and implemented for vehicles to cope with emergency affairs (e.g., security assistance, roadside repair), in case of a second accident. Although prohibited in normal scenarios, emergency lanes can act as normal lanes with identical standard as conventional carriage ways. During the May Day holiday of 2019, an exploratory test allowing temporary utilization of emergency lanes was performed on G42 freeway in China to maintain the traffic efficiency in the case of extremely large traffic volumes. In this paper, the characteristics of traffic flow parameters on both specific-lanes and the section are analyzed. The results show that only 12.4% of drivers decided to travel on the emergency lane. Further, the lane distribution took on different characteristics while the free flow speed (FFS) and the capacity of emergency lane were comparatively low. The road capacity after utilization of the emergency lane increased only by 5%.