An empirical study on heterogeneous traffic car-following safety indicators considering vehicle types

2021 ◽  
pp. 1-24
Author(s):  
Wenxuan Wang ◽  
Yanli Wang ◽  
Yanting Liu ◽  
Bing Wu
Keyword(s):  
Empirical Study ◽  
Heterogeneous Traffic ◽  
Car Following

Analyses of a continuum traffic flow model for a nonlane-based system

2014 ◽  
Vol 25 (10) ◽  
pp. 1450045 ◽  
Author(s):  
Arvind Kumar Gupta ◽  
Isha Dhiman
Keyword(s):  
Flow Model ◽  
Traveling Wave Solution ◽  
Heterogeneous Traffic ◽  
Density Functions ◽  
Lateral Separation ◽  
Homogeneous Case ◽  
Fundamental Diagram ◽  
Car Following ◽  
Lane Width ◽  
Car Following Model

We develop a heterogeneous continuum model based upon a car-following model for a nonlane-based system taking lateral separation into account. The criterion for linear stability analysis and traveling wave solution of the homogeneous case is studied. The consideration of the lateral separation not only stabilizes the flow but also shrinks the critical region. For heterogeneous case, the fundamental diagram is examined for two different equilibrium speed-density functions and the effect of lane width is investigated for different compositions of heterogeneous traffic. The theoretical findings agree well with the results of numerical simulation which justifies the applicability of the model to a nonlane-based system.

Application of Car-Following Systems to Queue Discharge Problem at Signalized Intersections

2002 ◽  
Vol 1802 (1) ◽  
pp. 205-213 ◽  
Author(s):  
Stephen L. Cohen
Keyword(s):  
Flow Problem ◽  
Fluid Model ◽  
Flow Speed ◽  
Signalized Intersections ◽  
Heterogeneous Traffic ◽  
Lane Changing ◽  
Car Following ◽  
Parameter Variations ◽  
Two Fluid Model ◽  
Two Fluid

The queue discharge problem at a signalized intersection was analyzed with application of the modified Pitt car-following system. The Pitt car-following system was implemented on an Excel spreadsheet in the form of a prototype simulation model. The situation consisted of a single intersection in which discharging vehicles were unconstrained by downstream conditions. It was asserted that the car-following parameters used in the queue discharge problem are significantly different from those used in the uninterrupted-flow problem and that this is consistent with the two-fluid model. A number of scenarios were executed for each situation, using the spreadsheet implementation to examine a number of issues, including the effect of the following: free-flow speed, car-following parameter variations, vehicle length, heterogeneous traffic streams, and lane changing. It was shown that all of these issues have significant effects on discharge headways and that the Pitt car-following system has a far wider range of applicability than the simple equal headway model. The intuitiveness of the findings and calibration and validation issues were also addressed.

scholarly journals Traffic Oscillations Mitigation in Vehicle Platoon Using a Car-Following Control Model for Connected and Autonomous Vehicle

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Zhijun Gao ◽  
Jiangfeng Wang ◽  
Xi Zhang ◽  
Jiakuan Dong ◽  
Lei Chen ◽  
...  
Keyword(s):  
Traffic Flow ◽  
Road Traffic ◽  
Autonomous Vehicle ◽  
Stopping Time ◽  
Control Model ◽  
Heterogeneous Traffic ◽  
Longitudinal Motion ◽  
Car Following ◽  
Vehicle Platoon ◽  
Traffic Oscillations

Traffic oscillations often occur in road traffic, they make traffic flow unstable, unsafe and inefficient. Emerging connected and autonomous vehicle (CAV) technologies are potential solutions to mitigating the traffic oscillations for the advantages that CAVs are controllable and cooperative. In order to study a control strategy and the effectiveness of CAVs in mitigating traffic oscillations and improving traffic flow and analyse the characteristics of homogeneous traffic flow made up of CAVs and heterogeneous traffic flow made up of CAVs and RVs when traffic oscillations appear in traffic flow. Firstly, the formation and propagation of traffic oscillations in a platoon of RVs are simulated and analysed. Then, a car-following control model is built to control the longitudinal motion of CAVs, and real-time information of preceding CAV is used in the model and this can make the motion of CAVs more cooperative. The model reflects an idea named “slow-in” and “fast-out,” and this idea is helpful to mitigate traffic oscillations. Then, numerical simulations of homogeneous traffic flow of a platoon of CAVs and simulations of heterogeneous traffic flow containing CAVs and RVs are conducted, and different penetration rates (0, 0.2, 0.4, 0.6, 0.8, and 1) of CAVs are considered in the simulations of heterogeneous traffic flow. The characteristics and evolution of traffic flow are analysed and some indexes reflecting traffic efficiency and stability are calculated and analysed. Simulation results show that there are smaller velocity fluctuation, less stopping time and shorter length of road occupied when vehicle platoon contains CAVs (penetration rates are from 0.2 to 1) compared to the platoon containing only RVs (without CAVs). As for the heterogeneous traffic flow containing CAVs and RVs, these three indexes decrease with the increase of penetration rates (from 0.2 to 1) of CAVs. These results indicate that CAVs with the car-following control model in vehicle platoon are beneficial for mitigating traffic oscillations and improving traffic flow.

scholarly journals Characteristic Analysis of Mixed Traffic Flow of Regular and Autonomous Vehicles Using Cellular Automata

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Yangzexi Liu ◽  
Jingqiu Guo ◽  
John Taplin ◽  
Yibing Wang
Keyword(s):  
Traffic Flow ◽  
Autonomous Vehicles ◽  
Road Traffic ◽  
Penetration Rate ◽  
Heterogeneous Traffic ◽  
Transport Systems ◽  
Traffic Density ◽  
Characteristic Analysis ◽  
Lane Changing ◽  
Car Following

The technology of autonomous vehicles is expected to revolutionize the operation of road transport systems. The penetration rate of autonomous vehicles will be low at the early stage of their deployment. It is a challenge to explore the effects of autonomous vehicles and their penetration on heterogeneous traffic flow dynamics. This paper aims to investigate this issue. An improved cellular automaton was employed as the modeling platform for our study. In particular, two sets of rules for lane changing were designed to address mild and aggressive lane changing behavior. With extensive simulation studies, we obtained some promising results. First, the introduction of autonomous vehicles to road traffic could considerably improve traffic flow, particularly the road capacity and free-flow speed. And the level of improvement increases with the penetration rate. Second, the lane-changing frequency between neighboring lanes evolves with traffic density along a fundamental-diagram-like curve. Third, the impacts of autonomous vehicles on the collective traffic flow characteristics are mainly related to their smart maneuvers in lane changing and car following, and it seems that the car-following impact is more pronounced.

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