To Merge Early or Late: Analysis of Traffic Flow and Energy Impact in a Reduced Lane Scenario

This paper analyzes the impact of late merging vehicles on traffic flow and energy efficiency via traffic microsimulation. Lane reductions, due to construction, road obstructions, or transitions to narrower roads, can be disruptive to traffic flow and energy efficiency of a stream of vehicles. In these instances, when there is heavy traffic flow a bottle-necking effect occurs at the reduction point. The backup of traffic is then propagated upstream causing vehicles to decelerate more often. As a result, fuel efficiency decreases and there is an increase in trip time. This research is motivated by recent articles [1] that indicate merging late could be beneficial when done in a coordinated manner. This paper will focus on a group of vehicles traveling along a high speed roadway with a lane closure. These vehicles employ a reactive Intelligent Driver Model with randomized parameters that mimic human-like car following. Our microsimulations show that, in general, high penetrations of late merging vehicles have a negative influence on traffic flow and energy efficiency. We consider a typical lane change behavior that does not involve coordination which could be the reason our results contradict those found from the Late Merge method [2] and other common lane change models [3] [4].