Cellular Automaton Traffic Flow Model Research Articles

Two Dimensional Cellular Automaton Model of the Mixed Traffic Flow for Urban Traffic

Based on the two-dimension cellular automaton traffic flow model (BML model), a mixed traffic flow model for urban traffic considering the transit traffic is established in this paper. Under the don't block the box rules and the opening boundary conditions, the impacts of transit traffic, the central station, traffic lights cycle, the vehicles length on the mixed traffic flow is studied by computer simulation. Some important characters appearing in the new model are also elucidated. It shows that traffic flow is closely related to traffic lights cycle, the geometric structure of transport network and boundary conditions. Under certain traffic light cycle time, the traffic flow has a periodical oscillation change. The comparison to practical measured data shows that our stimulation results are accordant with the changes of real traffic flow, which confirms the accuracy and rationality of our model.

Two dimensional mixed traffic flow considering the transit traffic

Based on the two-dimension cellular automaton traffic flow model (BML model), a mixed traffic flow model for urban traffic considering the transit traffic is established in this paper by using the Don't block the box rules. We have investigated the influences of the transit traffic ratio, and found that, in most cases, the urban traffic flow exhibited jam phase. Moreover, focusing on the traffic lights cycle, it is found that the average flow has the periodic fluctuation phenomenon, and we have explained this periodical oscillation change under different boundary conditions. The comparison to practical measured data shows that our stimulation results are accordant with the changes of real traffic flow, which confirms the accuracy and rationality of our model. DOI: http://dx.doi.org/10.11591/telkomnika.v10i8.1627 Full Text: PDF

A Stochastic Continuous Cellular Automata Traffic Flow Model with a Multi-agent Fuzzy System

We propose a new stochastic traffic flow model for highways (freeways), which is a hybrid between the classical cellular automata and the other microscopic traffic models, using continuous cellular automata. We combine the computational efficiency of cellular automata models with the accuracy of the microscopic models by introducing continuity in space. This continuity allows us to embed a multi-agent system based on fuzzy reasoning to simulate different driver-vehicle behaviours. The experimental results show that our model is able to reproduce the typical traffic flow phenomena with a variety of effects due to the heterogeneity within traffic stream.

A new three-step cellular automaton model considering a realistic driving decision

Most cellular automaton (CA) traffic flow models include four steps and take the velocity as the driver’s main concern. To better understand traffic behaviors, a new three-step CA model is studied, in which a realistic driving decision is divided into three stages: decision-making, action and result. The new model is novel in using the acceleration as a decision variable. It considers the deceleration limitation and proposes the maximum deceleration to be 2 cells per time step, based on real experimental data. Simulation results show that the model can reproduce the synchronized flow effectively and describe the phase transition well. Moreover, it can exhibit metastability and hysteresis if the slow-to-start effect is involved. Finally, a realistic application to systematic flow optimization is analyzed and an interesting result is obtained that a restriction of the inflow can lead to an improvement of the total flow through a bottleneck.

Path-preference cellular-automaton model for traffic flow through transit points and its application to the transcription process in human cells

We all use path routing everyday as we take shortcuts to avoid traffic jams, or by using faster traffic means. Previous models of traffic flow of RNA polymerase II (RNAPII) during transcription, however, were restricted to one dimension along the DNA template. Here we report the modeling and application of traffic flow in transcription that allows preferential paths of different dimensions only restricted to visit some transit points, as previously introduced between the 5' and 3' end of the gene. According to its position, an RNAPII protein molecule prefers paths obeying two types of time-evolution rules. One is an asymmetric simple exclusion process (ASEP) along DNA, and the other is a three-dimensional jump between transit points in DNA where RNAPIIs are staying. Simulations based on our model, and comparison experimental results, reveal how RNAPII molecules are distributed at the DNA-loop-formation-related protein binding sites as well as CTCF insulator proteins (or exons). As time passes after the stimulation, the RNAPII density at these sites becomes higher. Apparent far-distance jumps in one dimension are realized by short-range three-dimensional jumps between DNA loops. We confirm the above conjecture by applying our model calculation to the SAMD4A gene by comparing the experimental results. Our probabilistic model provides possible scenarios for assembling RNAPII molecules into transcription factories, where RNAPII and related proteins cooperatively transcribe DNA.

A Cellular Automaton Traffic Flow Model with Advanced Decelerations

A one‐dimensional cellular automaton traffic flow model, which considers the deceleration in advance, is addressed in this paper. The model reflects the situation in the real traffic that drivers usually adjust the current velocity by forecasting its velocities in a short time of future, in order to avoid the sharp deceleration. The fundamental diagram obtained by simulation shows the ability of this model to capture the essential features of traffic flow, for example, synchronized flow, meta‐stable state, and phase separation at the high density. Contrasting with the simulation results of the VE model, this model shows a higher maximum flux closer to the measured data, more stability, more efficient dissolving blockage, lower vehicle deceleration, and more reasonable distribution of vehicles. The results indicate that advanced deceleration has an important impact on traffic flow, and this model has some practical significance as the result matching to the actual situation.

Properties of vehicle gap distribution in the mixed traffic flow

Using the cellular automaton traffic flow model, we study the vehicle gap distribution of the mixed traffic flow under the different delay probability and the different mixing rate for given vehicle density. Computer simulation results show that the delay probability has no effect on the vehicle gap distribution for the case of the high vehicle density; whereas, for the cases of the low and intermediate vehicle density, the delay probability has great effect on the vehicle gap distribution. Furthermore, one notes that the mixing rate has great effect on the vehicle gap distribution for the case of the low vehicle density.

Phase diagrams on an unsignalized intersection for the cases of different maximum velocities of vehicles

Using the cellular automaton traffic flow model, we investigate an unsignalized intersection which consists of two perpendicular one-lane roads. Both the roads cross at a point and the intersecting roads are cyclic. Each vehicle may pass or occupy the intersection where all the vehicles on both roads are not allowed to turn. Different from Ishibashi and Fukui’s studies in which the update is carried out for both roads in turn, the parallel update is proposed and its detailed rules are presented in our model. In this work, the cases of different maximum vehicle velocities on both roads are considered. Based on simulation results and the principle for constructing phase diagrams, phase diagrams are mapped out and their specific flow formulas for all the regions in the phase diagrams are obtained for various vehicle densities, which are seldom done in previous studies. One also finds that the topology of phase diagrams depends on the update rules of eastbound and northbound roads and their maximum velocities of vehicles.

A Modified Cellular Automaton in Lagrange Form with Velocity Dependent Acceleration Rate

Based on Nasch model of single lane traffic flow, a modified Cellular Automaton traffic flow model incorporating s-t-s effect among vehicles given in Lagrange model for traffic flow is proposed to simulate homogeneous and mixed type traffic flow. The model is developed with modified cell size, incorporating different acceleration characteristics depending upon the speed of each individual vehicle. Comparisons are made between Nasch model and modified model. It is observed that slope of congested branch is changed for modified model due to variable acceleration rate. 

A Modified Cellular Automaton in Lagrange Form with Velocity Dependent Acceleration Rate

Based on Nasch model of single lane traffic flow, a modified Cellular Automaton traffic flow model incorporating s-t-s effect among vehicles given in Lagrange model for traffic flow is proposed to simulate homogeneous and mixed type traffic flow. The model is developed with modified cell size, incorporating different acceleration characteristics depending upon the speed of each individual vehicle. Comparisons are made between Nasch model and modified model. It is observed that slope of congested branch is changed for modified model due to variable acceleration rate.

The influence of nonmonotonic synchronized flow branch in a cellular automaton traffic flow model

In this paper we study the congested patterns upstream of an isolated on-ramp in a cellular automaton traffic flow model, which is proposed in our previous paper [Cheng-Jie Jin, Wei Wang, Rui Jiang, Kun Gao, J. Stat. Mech (2010) P03018]. The simulation results under open boundary conditions are presented by spatiotemporal diagrams. Our diagram of congested patterns is quite similar to that of the cellular automaton models within Kerner’s three-phase traffic theory, while some differences in the “moving synchronized flow pattern” (MSP) should be noted. In our model the upstream front of MSP propagates not only upstream, but also downstream. The propagation direction depends on the flow rates and densities of free flow and synchronized flow. Besides, in our model the outflow of wide moving jams or bottlenecks could be free flow or synchronized flow, as reported in many empirical data. In the dissolving of congestions, the form of free flow may be hindered and stable synchronized flow may emerge. This phenomenon can help us understand more about the outflow. All the interesting characteristics of our model are due to the nonmonotonic structure of synchronized flow branch in the fundamental diagram, which has not been found in previous models.

Effect of acceleration threshold on the phase transition in a cellular automaton traffic flow model

In this paper, we incorporate new parameters into a cellular automaton traffic flow model proposed in our previous paper [Jin et al. 2010 J. Stat. Mech. 2010 P03018]. Through these parameters, we adjust the anticipated velocity and the acceleration threshold separately. It turns out that the flow rate of synchronized flow mainly changes with the anticipated velocity, and the F → S phase transition feature mainly changes with the acceleration threshold. Therefore, we conclude that the acceleration threshold is the major factor affecting the F → S phase transition.

Phase coexistence induced by a defensive reaction in a cellular automaton traffic flow model

Traffic flow modeling is an elusive example for the emergence of complexity in dynamical systems of interacting objects. In this work, we introduce an extension of the Nagel–Schreckenberg (NaSch) model of vehicle traffic flow that takes into account a defensive driver’s reaction. Such a mechanism acts as an additional nearest-neighbor coupling. The defensive reaction dynamical rule consists in reducing the driver’s velocity in response to deceleration of the vehicle immediately in front of it whenever the distance is smaller than a security minimum. This new mechanism, when associated with the random deceleration rule due to fluctuations, considerably reduces the mean velocity by adjusting the distance between the vehicles. It also produces the emergence of bottlenecks along the road on which the velocity is much lower than the road mean velocity. Besides the two standard phases of the NaSch model corresponding to the free flow and jammed flow, the present model also exhibits an intermediate phase on which these two flow regimes coexist, as it indeed occurs in real traffics. These findings are consistent with empirical results as well as with the general three-phase traffic theory.

Cellular automaton model with time gap dependent randomisation under Kerner's three-phase traffic theory

In this article, a new cellular automaton traffic flow model, in which randomisation effect is enhanced with the decrease of time gap and the long time stopped vehicle has large randomisation probability, is presented. Both periodic and open boundary conditions are considered. Under periodic boundary condition, the fundamental diagram and the properties of synchronised flow are studied in detail. Under open boundary condition, different congested patterns induced by an on-ramp are analysed. The results are consistent with the well-known results of Kerner's three-phase traffic theory published before.

A traffic flow cellular automaton model to considering drivers' learning and forgetting behaviour

It is known that the commonly used NaSch cellular automaton (CA) model and its modifications can help explain the internal causes of the macro phenomena of traffic flow. However, the randomization probability of vehicle velocity used in these models is assumed to be an exogenous constant or a conditional constant, which cannot reflect the learning and forgetting behaviour of drivers with historical experiences. This paper further modifies the NaSch model by enabling the randomization probability to be adjusted on the bases of drivers' memory. The Markov properties of this modified model are discussed. Analytical and simulation results show that the traffic fundamental diagrams can be indeed improved when considering drivers' intelligent behaviour. Some new features of traffic are revealed by differently combining the model parameters representing learning and forgetting behaviour.

A two-lane cellular automaton traffic flow model with the influence of driving psychology

A two-lane cellular automaton model is developed to analyze the urban traffic flow with considering the influence of driving psychology. In order to show the different psychological characters of drivers when changing lane and braking, lane-changing choice probability and safety parameter are introduced. By computer simulation, the relationships among speed, density and traffic volume are given to show the influence of driving psychology on the traffic flow. The simulation results indicate that the lane-changing choice probability has little effect on the average speed, but it makes the variance of speed larger. And the safety parameter can increase the average speed and the traffic volume.

Cellular automaton traffic flow model considering influence of accidents

Based on the NaSh model, considering the influence of traffic accident and maintenance of highway sections on traffic flow, the cellular automaton model of highway traffic flow under the lane control is established when accident occurs. And the relevant data of the model are calculated. Through analyzing the results of numerical simulation it is found that the accident has a great influence on the highway traffic flow and considerably on traffic flow density within a certain range. And the influence of the accident blocking point on traffic flow on lane 1 is less than on lane 2. Meanwhile, in this range of traffic flow density, the longer the blocking time and the length of blocking section, the greater the influence of traffic flow is.

Energy dissipation of the mixed traffic system with automatic cruise

Based on the cellular automaton traffic flow model of automatic cruise controlling, the influences of speed maximum, mixing ratio, expectation factor of speed, and mass of vehicle on energy dissipations of the mixed traffic system are studied. Through computer simulation, the energy dissipations of mixed traffic system under the different parameters are obtained and analysed by the mean field theory. The theoretical analyses are consistent with the results of numerical simulation.

Effect of speed fluctuations due to driving imperfections on road traffic noise emission

Propagation of traffic noise in metro cities is a complex phenomenon. Since fluctuations in traffic flow are basic nature of a traffic stream, it can be studied by using Cellular Automata (CA). Braking tendencies among vehicles which reflect the driving imperfections affect the overall traffic flow. CA traffic flow model gives the wide description of stochastic nature of traffic flow. The present study reveals the influence of stochastic nature of traffic flow over traffic noise emission. Vehicles are classified into 7 types. To simulate traffic flow CA is used with simple updated rules for movement of vehicles. Stochastic CA is used for calculating flow, average speed and equivalent Sound Pressure Level (SPL) of traffic stream for various densities. Influence of speed fluctuations in continuous traffic streams over the noise emission level of different types of vehicles has been studied in conditions in India. A value of braking parameter p has been estimated for road conditions in India which is found suitable when compared with real observed data.

Two-lane traffic-flow model with an exact steady-state solution

We propose a stochastic cellular-automaton model for two-lane traffic flow based on the misanthrope process in one dimension. The misanthrope process is a stochastic process allowing for an exact steady-state solution; hence, we have an exact flow-density diagram for two-lane traffic. In addition, we introduce two parameters that indicate, respectively, driver's driving-lane preference and passing-lane priority. Due to the additional parameters, the model shows a deviation of the density ratio for driving-lane use and a biased lane efficiency in flow. Then, a mean-field approach explicitly describes the asymmetric flow by the hop rates, the driving-lane preference, and the passing-lane priority. Meanwhile, the simulation results are in good agreement with an observational data, and we thus estimate these parameters. We conclude that the proposed model successfully produces two-lane traffic flow particularly with the driving-lane preference and the passing-lane priority.