Improving Traffic Flow Efficiency at Motorway Lane Drops by Influencing Lateral Flows

Abstract

Lane drops are a common bottleneck source on motorway networks. Congestion sets in upstream of a lane drop as a result of the lane changing activity of merging vehicles. This causes the queue discharge rate at the bottleneck to decrease and drop below the capacity, leading to capacity drop and further congestion. The objective of this study is to minimize the total travel time of the system by controlling lateral flows upstream of the lane drop. This is equivalent to maximizing the exit flows at the bottleneck. An optimization problem is formulated for a 3–2 lane drop section with high inflow. The problem is solved for different test cases where the direction of lateral flows being controlled is varied. An incentive based macroscopic model representing the natural lane changing scenario is used as a benchmark for comparison. The results showed that by influencing the lateral flows upstream of the bottleneck, the queue discharge rate increased by more than 4.5%. The total travel time of the system was consequently found to be reduced. The improvements in performance were primarily a result of the distribution of lane changing activity over space and the balancing of flow among the lanes which lead to the decrease in the severity of congestion. The findings reveal a potentially effective way to reduce the severity of congestion upstream of lane drop bottlenecks during high demand which could be implemented using roadside and in-car advisory systems.

A Multi-Class Lane-Changing Advisory System for Freeway Merging Sections Using Cooperative ITS

“…This LTI system in (11) can be used to formulate an optimal control problem that is aimed at maximizing traffic efficiency by balancing flows among lanes on a freeway. A ∈ R H ×H , composed of a rs elements, represents the connection between pairs of subsequent cells connected by a longitudinal flow and B ∈ R H ×F , composed of b rs elements, reflects the connection of adjacent cells connected by lateral flows.…”

“…The problem defined in ( 18) is subject to the linear dynamics presented in (11). Assuming the system is stabilizable and detectable, we can solve this type of problem using a linear quadratic regulator.…”

“…Although these approaches can be applied in real-time, they require enough knowledge about the traffic system to generate a set of instructions. In [9]- [11], the lane assignment problem is treated as an optimization program. However, the inherent computational processing time associated with these approaches might hinder their real-time applicability.…”

Lane Change Control Combined with Ramp Metering: A Strategy to Manage Delays at On-Ramp Merging Sections

“…We employ the LC control framework proposed in Nagalur Subraveti et al [46] in this study. For a detailed description of the framework, the authors refer to the original work.…”

Ramp Metering with Microscopic Gap Detection Algorithm Design and Empirical Acceleration Verification

“…This is useful, since vehicles that leave the main road could potentially create gaps for the merging vehicle to merge into. If significantly more vehicles desire to merge onto the main road than leave it, there might be a need for actively creating gaps at the righthand lane of the main road (21). The impact of varying the HGV fraction, maximum speed limit and average demands compared with the base case scenario will be noted in the section ''Sensitivity analysis'' (Table 3).…”