Unravelling effects of cooperative adaptive cruise control deactivation on traffic flow characteristics at merging bottlenecks
Department of Transport and Planning, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN Delft, the Netherlands
Abstract
CACC 交接对汇入区的影响。
Existing CACC traffic flow models have not yet been able to reproduce realistic CACC vehicle behaviour and pay little attention to the influence of system deactivation on traffic flow at bottlenecks.
results: CACC MPR indeed increased the roadway capacity. However the resulting capacity in the merging bottleneck is much lower than the pipeline capacity and capacity drop persists in bottleneck scenarios at all CACC MPR levels
Introduction
的影响因素：
The individual time headway is determined by the inter-vehicle spacing, vehicle length, and travelling speed + vehicle type
异质车辆类型对交通流有很大影响
it is found that the roadway capacity is sensitive to the ratios of vehicle classes in mixed traffic, due to various time gap settings for each vehicle class
Introducing 10% new vehicles with large desired time gap could lead to a capacity reduction of 15% at a highway segment and of 40% at a merging sectionx`
解析方法的局限性
Analytical approaches are based on macroscopic traffic flow models and allow us to identify and explain the impact of a limited number of factors introduced by CACC vehicles. However, analytical approaches typically model the traffic flow in equilibrium states, and do not capture well the nonlinear phenomena in traffic flow such as flow instability and capacity drop
MPR：market penetration rate
CACC 对lane drop 的影响：
using CACC vehicles has potential positive impacts on the roadway capacity near a lane drop but a low CACC penetration below 40% does not show significant effects.
最关键的是 CACC time gap
CACC time gap setting plays a determinate role in the resulting capacity in simulations and a higher desired time gap leads to a lower attainable capacity increase
当前CACC 研究的问题：
(1) using vehicle control algorithm as car-following response;
(2) no authority transitions involved with CACC operation;
(3) overestimated CACC performance in maintaining desired time gaps less than 0.5 s
(4) infinite CACC string length.
The actual impacts of CACC vehicles on road flows remain uncertain.
CACC behaviour model
the accelerations from ACC/CACC models are limited to a range from −4m/s2 to 2m/s2.
