On-ramp System Research Articles

Traffic Dynamics of Bicycle Flow: Experiment and Modeling

Cycling has been advocated by many governments because it is a healthy and green transportation mode and it helps mitigate traffic congestion. However, compared with vast amounts of works on vehicle flow and pedestrian flow, the bicycle flow study currently lags behind. We have carried out experimental studies on bicycle flow on a 146 meters long circular road and on an on-ramp system. We present the fundamental diagram of bicycle flow and the trajectories of each bicycle on the circular road. We have analyzed the spatiotemporal evolution of bicycle flow and found that jams spontaneously form above a critical density of approximately 0.37 bicycles/m. For the on-ramp system, no capacity drop has been observed. The similarity and difference between bicycle flow and vehicle flow has been discussed. We propose a cellular automaton model of bicycle flow, and the simulation results are in agreement with the experiments.

The influence of heavy vehicles on traffic dynamics around on-ramp system: Cellular automata approach

Although the on-ramp system has been widely studied, the influence of heavy vehicles is unknown because researchers only investigate the traffic dynamics around on-ramp system under homogeneous traffic conditions, which is different in real-world settings. This paper uses an improved cellular automaton model to study the heterogeneous traffic around on-ramp system. The forward motion rules are improved by considering the differences of driving behavior in different vehicle combinations. The lane change rules are improved by reflecting the aggressive behavior in mandatory lane changes. The phase diagram, traffic flow, capacity and spatial-temporal diagram are analyzed under the influences of heavy vehicles. The results show that by increasing the percentage of heavy vehicles, there will be more severe traffic congestion around on-ramp system, lower saturated flow and capacity. Also, the interactions between main road and on-ramp have been investigated. Increasing the percentage of heavy vehicles at the upstream of the conflict area on the main road or restricting heavy vehicles on the outside lane of the main road will deteriorate the performance of on-ramp. While the main road will have better performance as the percentage of heavy vehicles on the on-ramp increases when the on-ramp inflow rate is not low.

A hybrid traffic flow model with considering the influence of adaptive cruise control vehicles and on-ramps

Recently, autonomous vehicles and the relevant studies have attracted much attention. Adaptive cruise control (ACC), which is a kind of cruise control system for vehicles, automatically adjusts the vehicle speed to maintain a safe distance from vehicles ahead. Since the vehicle with ACC (called ACC vehicles) is semi-autonomous, the performance of ACC vehicle must be quite different from that of manual vehicle. The characteristics of traffic flow with ACC vehicles should be carefully investigated, especially when the traffic system is a bit complicated, such as on-ramp system. The primary objective of this paper is to propose a traffic flow model to simulate the traffic flow with considering the influence of ACC vehicles and on-ramps. Based on the model proposed by Yuan in 2009 [Yuan Y M 2009 Ph. D. Dissertation (Hefei: University of Science and Technology of China)], a hybrid traffic flow model with considering the influence of ACC vehicles and on-ramps is developed. Considering the differences between ACC and manual vehicles, a car-following sub-model based on constant time headway principle is developed for ACC vehicles, while an MCD cellular automata sub-model is proposed for manual vehicles. Besides, a new parameter, , is introduced to show different psychologies of drivers when changing lane from on-ramp to main road. The lane-changing model for vehicles on-ramp is developed as well. At the end, numerical simulation is demonstrated to study the influence of ACC vehicles on traffic flow at on-ramp, and to reveal the influence of parameters on the proposed hybrid model (i.e., the length of merge area, the desired time headway of ACC vehicle and ) on model performance. The results of this paper are as follows. 1) When the ACC vehicles exist in a traffic system, the performance of traffic flow in a on-ramp area is improved: the influence of merged vehicles on main road is reduced, and the average speed and volume are increased. 2) The increase of ACC vehicles can help to alleviate traffic congestion in both congestion duration and scope aspects. 3) The newly proposed hybrid model is sensitive to the length of merge area lw, the desired time headway of ACC vehicle Hd and lane-changing psychology parameter : the decrease of Hd and the increase of can both improve the average speed and volume of traffic flow. In addition, when the volume of on-ramp is small, the speed and volume of main road can be improved by enlarging lw. When the volume of on-ramp is large, a small lw will be better for traffic flow.

Cellular automata model simulating traffic car accidents in the on-ramp system

In this paper, using Nagel–Schreckenberg model we study the on-ramp system under the expanded open boundary condition. The phase diagram of the two-lane on-ramp system is computed. It is found that the expanded left boundary insertion strategy enhances the flow in the on-ramp lane. Furthermore, we have studied the probability of the occurrence of car accidents. We distinguish two types of car accidents: the accident at the on-ramp site (Prc) and the rear-end accident in the main road (Pac). It is shown that car accidents at the on-ramp site are more likely to occur when traffic is free on road A. However, the rear-end accidents begin to occur above a critical injecting rate αc1. The influence of the on-ramp length (LB) and position (xC0) on the car accidents probabilities is studied. We found that large LB or xC0 causes an important decrease of the probability Prc. However, only large xC0 provokes an increase of the probability Pac. The effect of the stochastic randomization is also computed.

Study on the Traffic Behavior of On-Ramp System Considering Driver Behavior

based on the main road into a two lane entrance ramp system the open boundary conditions, using the asymmetric lane changing rules, considering driver behavior characteristics, from standpoint of safety driving ,simulate the entrance ramp system. We get a basic road map different entrance probability of flow, velocity, and analyze the driving safety.compared with reference, and the reference results show that after considering driver behavior, in the ramp at the interface, reduce the interaction with the main ramp,not only the system traffic flow in each section is improved, and but also improve the driving safety.Considering the entrance ramp system driver behavior can be simulated more in line with the running state of the vehicle in real life.

The Vehicle’s Lane-Changing Rules of On-Ramp System

In order to observe the feather of traffice of on-ramp system in simulation experiments more truly, four different lane changing rules are presented based on the point of safe-distance. Experiment results show that the lane changing rules do have an important impact on the traffic flow of on-ramp system. The rule without safe-distance could make the capacity of the on-ramp section get its biggest value, while the capacity of upstream and downstream of main road both gets brought down; the rule considering forward and backward safe-distance could make the upstream section, downstream section and the whole system get their biggest value.

Simulation Research on On-ramp Traffic Flow Based on Cellular Automata

In order to analyze characteristic of on-ramp traffic flow, a new traffic model of on-ramp system based on the cellular automaton traffic model have been built according to the behavior of changing lane form point of safe distance, and on that basis, four different lane changing rules were put forward, and Affection of four kinds of lane changing rules on-ramp system were analyzed, in the meanwhile, the complex behavior of traffic flow of on-ramp system were discuss. Finally, characteristic of on-ramp traffic flow based on the cellular automaton traffic have been carried out to simulate in order to testify validity, objectivity and applicability by using calculating and comparing analysis. The simulation results show that the lane-changing behavior has a huge effect on the flow of ramp model, and the behavior without considering safe-distance could make the flow of on-ramp section reach the highest point, while the flow of upstream and downstream sections of main road could be obviously suppressed.

Dynamic Congested Traffic States of Density Difference Lattice Hydrodynamic Model with On-Ramp

The density difference lattice hydrodynamic model with on-ramp is proposed. Stochastic and deterministic rules for the on-ramp flow entering into the main road are designed. Under the stochastic rule, various empirical spatiotemporal patterns can be well reproduced, such as the pinned localized cluster (PLC) and homogeneous synchronized traffic (HST). Under the deterministic rule, four new types of congested traffic states, such as the stationary oscillatory congested traffic (OCT) upstream of on-ramp and the stationary and localized OCT emerging in HST, are identified for the first time. Comparisons with the macroscopic speed gradient model are carried out, and some advantages of our model are clarified. To our knowledge, it is the first research showing that the lattice hydrodynamic model could reproduce various congested patterns induced by the on-ramp system.

Starting Energy Dissipation of Traffic Flow with On-Ramp

The starting energy dissipation of on-ramp system with open boundary condition is investigated by means of cellular automata simulations. We study the influence of the injection rate of on-ramp, the injection rate of main road and the removal rate of main road on the starting energy dissipation of each road. It is found that even though the injection rates neither of on-ramp nor main road have influence on the starting energy dissipation when critical values achieved, the removal rate of main road has a major impact on the starting energy dissipation of the system all along.

A Traffic Control Method Based on the Congestion Mechanism in an on-Ramp Traffic System with a Nearby Bus Stop

In this paper, a control method based on the congestion mechanism is proposed in an on-ramp system with a nearby bus stop. The basic idea is to limit on-ramp vehicles entering main road when the traffic condition between on-ramp and the bus stop becomes worse, since traffic congestion is caused by traffic interaction between them. The simulation results show that the control method can reduce the vehicles’ collision between the main road and the on-ramp. The congestion on both main road and the on-ramp are alleviated. Comparisons between this method and previous one for single on-ramp control are made. The method in this paper can help main road remaining a good condition with only little drop-off of the on-ramp capacity. And traffic conditions on both main road and the on-ramp are better with the control of our method.

Traffic Congestion Mechanism in Two Ramp Systems

The aim of this paper is to study traffic properties in an on/off-ramp system with a bus stop close to the on/off ramp. The location of the bus stop in the on/off-ramp (thereafter downstream or upstream case) is discussed. The simulation results show that in the two ramp systems, the reasons for traffic congestions are different. In the on-ramp system, buses and cars coming from on-ramp interweave each other, while in the off-ramp system, buses interweave with cars exiting to off-ramp. Thus, in the on-ramp (off-ramp) system, the upstream (downstream) bus stop is helpful to reduce the interweaving situation. Moreover, the negative effect will disappear when the distance between the bus stop and the on/off-ramp is more than 20 cells (i.e. 150 m). These qualitative findings may provide some suggestions on traffic management and optimization.

Efficiency promotion for an on-ramp system based on intelligent transportation system information

The effect of cars with intelligent transportation systems (ITSs) on traffic flow near an on-ramp is investigated by car-following simulations. By numerical simulations, the dependences of flux on the inflow rate are investigated for various proportions of cars with ITSs. The phase diagrams as well as the spatiotemporal diagrams are presented to show different traffic flow states on the main road and the on-ramp. The results show that the saturated flux on the main road increases and the free flow region is enlarged with the increase of the proportion of cars with ITS. Interestingly, the congested regions of the main road disappear completely when the proportion is larger than a critical value. Further investigation shows that the capacity of the on-ramp system can be promoted by 13% by using the ITS information, and the saturated flux on the on-ramp can be kept at an appropriate value by adjusting the proportion of cars with ITS.

Traffic dynamics of an on-ramp system with a cellular automaton model

This paper uses the cellular automaton model to study the dynamics of traffic flow around an on-ramp with an acceleration lane. It adopts a parameter, which can reflect different lane-changing behaviour, to represent the diversity of driving behaviour. The refined cellular automaton model is used to describe the lower acceleration rate of a vehicle. The phase diagram and the capacity of the on-ramp system are investigated. The simulation results show that in the single cell model, the capacity of the on-ramp system will stay at the highest flow of a one lane system when the driver is moderate and careful; it will be reduced when the driver is aggressive. In the refined cellular automaton model, the capacity is always reduced even when the driver is careful. It proposes that the capacity drop of the on-ramp system is caused by aggressive lane-changing behaviour and lower acceleration rate.

A modified weighted probabilistic cellular automaton traffic flow model

This paper modifies the weighted probabilistic cellular automaton model (Li X L, Kuang H, Song T, et al 2008 Chin. Phys. B 17 2366) which considered a diversity of traffic behaviors under real traffic situations induced by various driving characters and habits. In the new model, the effects of the velocity at the last time step and drivers' desire for acceleration are taken into account. The fundamental diagram, spatial-temporal diagram, and the time series of one-minute data are analyzed. The results show that this model reproduces synchronized flow. Finally, it simulates the on-ramp system with the proposed model. Some characteristics including the phase diagram are studied.

Study on the traffic behavior of on-ramp system with two-lane main road under signal controlling

In this paper we investigate the two-lane main road on-ramp system with signal-controlling using the cellular automata traffic flow model. The traffic signal is setup at the merging part between the main road and the on-ramp so that it can control the vehicles of both roads. We simulate the effect of traffic signal on vehicle flows of main road and on-ramp, and the traffic capacity and average velocity at the merging part are discussed. Through the analysis of the phase diagram, it can be found that the on-ramp system with two-lane main road can embody more complicated and realistic traffic flow characteristics than the on-ramp system with single-lane main road. Compared with the model introduced by Jiang Rui ［Jiang R 2003 J. Phys. A 36 11713］, the simulation results indicate that the state of traffic flow is improved obviously and the capacity of the on ramp system has increased.

ENHANCING HIGHWAY CAPACITY BY HOMOGENIZING TRAFFIC FLOW

This paper studies the capacity of a highway with an on-ramp, using a cellular automaton (CA) model. This CA model is in the framework of three phase traffic theory and can reproduce the first order phase transition from the free flow to synchronized flow (Jiang and Wu, 2005, European Physical Journal B, 46, 581–584). It is shown when some special homogeneous boundary conditions are used, the capacity of the on-ramp system is greatly enhanced because the strong interactions of main road vehicles and on-ramp vehicles, which occur under inhomogeneous boundary conditions, are avoided. Based on this finding, we propose a new design of road section upstream of on-ramp, i.e., to split the main road into several branches and then the branches merge together. With the help of traffic light control, the inhomogeneous vehicles are homogenized. Accordingly, the capacity is enhanced.

Traffic behavior in the on-ramp system with signal controlling

In this paper, we investigate the on-ramp system on the highway using cellular automaton traffic model. Different from previous work, we introduce traffic signal to control the vehicle flows on the main road and the on-ramp. A method of signal controlling is presented, and the update rule in special road is given in detail according to the stimulation role of signal to the drivers. The simulation results show that, the phase diagram of on-ramp system is divided into three regions. The currents of the on-ramp system are discussed. Under the control role of traffic signal, the vehicle flows of the main road and the on-ramp can become orderly. The capacity of the system may keep a maximum value. In addition, the drastic velocity fluctuation is discussed near the on-ramp. A dangerous condition in Jiang et al. [Phys. Rev. E 66 (2002) 036104] can be effectively avoided.

The effect of restricted velocity in the two-lane on-ramp system

Usually there are multi-lane on the main road of the on-ramp system. The drivers may decelerate for more safety when they are near the on-ramp. In addition, the car velocity may be restricted according to the traffic regulation. In this paper, we study phenomenon using the cellular automata traffic flow model. We find that: (i) the phase diagram of the two-lane on-ramp system appears a new region, in which the traffic of the on-ramp reaches maximum flow. (ii) The introduction of restricted velocity region will decrease capacity of the on-ramp, but reduce the drastic velocity fluctuation near the on-ramp.

The effects of accelerating lane in the on-ramp system

Usually there is an accelerating lane as an on-ramp merges with the main road. How the length of this section and the traffic regulations influence the traffic behaviors has seldom been investigated. In this paper, we study this issue using the cellular automata traffic flow model. We find that (i) the permission of lane changing from main road to the accelerating lane will deteriorate the capacity of the road, hence it should be forbidden; (ii) when lane changing from main road to accelerating lane is forbidden, the introduction of an accelerating lane can improve the capacity of the on-ramp system.

The effects of accelerating lane in the on-ramp system

Usually there is an accelerating lane as an on-ramp merges with the main road. How the length of this section and the traffic regulations influence the traffic behaviors has seldom been investigated. In this paper, we study this issue using the cellular automata traffic flow model. We find that (i) the permission of lane changing from main road to the accelerating lane will deteriorate the capacity of the road, hence it should be forbidden; (ii) when lane changing from main road to accelerating lane is forbidden, the introduction of an accelerating lane can improve the capacity of the on-ramp system.