Tunnel Traffic Evolution during Capacity Drop Based on High-Resolution Vehicle Trajectory Data

Abstract

Capacity drop is the critical phenomenon that triggers traffic congestion, while traffic evolution is very complex during a capacity drop. This study applied the empirical vehicle trajectory data to explore the traffic characteristics during the capacity drop at the tunnel bottleneck section. We first construct a capacity drop analysis model using image processing technology to extract high-precision vehicle trajectories. We then analyze the characteristics of the evolution process of the capacity drop at the bottleneck area. The results show that the capacity drop is a dynamic evolution process from free flow to congested flow where traffic operation is distinct. The capacity drop shows the difference between congested flow and non-congested flow. The driving characteristics of drivers in the two states are also different. The influence of lane-changing behavior on the capacity drop is estimated. In the free flow state, the disturbance caused by lane-changing can be quickly eliminated. With the increase in vehicle numbers in the area, the frequent lane-changing behavior accumulates disturbance. When the disturbance reaches a certain degree, congestion will occur, and the vehicle’s speed will drop sharply, resulting in a capacity drop.

Research on Calculating Traffic Capacity in Extra-Long Subsea Tunnels—A Case Study of the Qingdao Jiaozhou Bay Subsea Tunnel

“…2 Because the tunnel markings are mostly solid lines, vehicles entering the tunnel are limited in their ability to choose a lane, resulting in low utilization of the right lane. 3 Due to the side wall effect, which the tunnel's side wall will have on the driver's psychology, the driver will be more inclined to choose the middle lane.…”

“…2 Traffic composition-the mix of different types of vehicles on the road and the proportion of different vehicle types are important factors affecting the distribution of speed; the subsea tunnel provides for large vehicles to drive on the right, making the right lane speed significantly lower than the left lane and the middle lane. 3 Road factors, changes in slope and curve radius in the subsea tunnel, and the design of traffic markings will all have an impact on vehicle speed. 4 Environmental factors-bright and dark adaptation of drivers at tunnel entrances and exits leads to fluctuations in vehicle speed.…”

“…For instance, the Highway Capacity Manual has identified road condition, traffic, and technical factors as critical elements influencing highway capacity [2]. Yang et al [3] investigated the impact of lane-changing behavior on capacity reduction, while Anders et al [4] studied the effect of public information on highway tunnel capacity. Mostafa et al [5] investigated how tunnel structure affects capacity, and Cai [6] used numerical simulation to determine the main influencing factors on traffic capacity, including slope, slope length, and the proportion of large vehicles.…”

“…This paper aims to examine the impact of various factors related to the road environment and control measures on tunnel traffic capacity. Unlike the existing literature [3][4][5][6][7][8][9][10][11][12][13], which focuses mainly on single factors and neglects the interplay between multiple factors, this paper considers a combination of factors that could potentially influence traffic capacity. By analyzing both single and multiple factors, the paper seeks to provide a more comprehensive understanding of the complex dynamics involved in tunnel traffic capacity.…”