Empirical analysis of traffic flow characteristics at variable approach lanes

It is interesting that despite its long-term and widespread use in China, relatively little is known about the operational characteristics of a variable approach lane (VAL) in real world. Using one month of inductive-loop detector data at ten dynamic approaches (intersection approaches with dynamic lane assignment) from different intersections in Hangzhou, China, this paper presents the results of a study materializing the flow characteristics of variable approach lanes by comparing them with adjacent normal-flow lanes under various operating conditions. The effectiveness of the results was examined in a case-control analysis by integrating 12 fixed approaches (without variable lane) as benchmark. It was found that the difference or similarity of flow rate between the variable lane and the normally-flowing lane differs under a variety of traffic volume, time-of-day, mode-of-operation, and overhead lane-use guidance sign (OHS) location conditions. The study also revealed that while naturally there may be a difference in the flow rates between referencing lanes at fixed approaches, the flow difference percentage (FDP) at dynamic approaches is significantly higher.