A cellular automata model for urban traffic with multiple roundabouts (original) (raw)
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Modeling traffic flow at a single-lane urban roundabout
Computer Physics Communications, 2002
In this paper, we propose a new model to study traffic flow at a single-lane urban roundabout, using a multi-state cellular automata (CA) ring under the offside-priority rule (by which a vehicle entering gives way to one already on the roundabout). Each vehicle entering the roundabout is randomly characterized by a predetermined exit with specified probability. Driver behavior at the roundabout entrance is randomly grouped into four categories based on space required to enter the roundabout. Three aspects of roundabout performance in particular have been studied. The first looks at overall throughput (the number of vehicles that navigate the roundabout in a given time). This is considered for different geometries, turning and arrival rates (vehicles arrive at random with a Poisson distribution, with parameter λ 0.5 in general for free flow). The second investigates changes in queue length, delay time and vehicle density (ratio of the number vehicles to the number of cells) for an individual road. The third considers the impact of driver choices on throughput and operation of the roundabout. We find that throughput is influenced by the topology of the roundabout and turning rates, but only incidentally by size. Throughput reaches a maximum for critical arrival rate on one or more roads. Driver behavior has considerable impact on overall performance, with rapid congestion resulting from reckless choices. Vehicles drive on the left in Ireland, but rules are generally applicable.
Characteristics of vehicular traffic flow at a roundabout
Physical Review E, 2004
We construct a stochastic cellular automata model for the description of vehicular traffic at a roundabout designed at the intersection of two perpendicular streets. The vehicular traffic is controlled by a self-organized scheme in which traffic lights are absent. This controlling method incorporates a yield-at-entry strategy for the approaching vehicles to the circulating traffic flow in the roundabout. Vehicular dynamics is simulated within the framework of the probabilistic cellular automata and the delay experienced by the traffic at each individual street is evaluated for specified time intervals. We discuss the impact of the geometrical properties of the roundabout on the total delay. We compare our results with traffic-light signalisation schemes, and obtain the critical traffic volume over which the intersection is optimally controlled through traffic light signalisation schemes.
Cellular Automata and Roundabout Traffic Simulation
Lecture Notes in Computer Science, 2004
A new software package, named Archirota, for simulating traffic in roundabouts is introduced. Its simulation module is entirely based on cellular automata and is automatically configured for real-world geocoded data. Archirota can be used both as a support for designing new roundabout and for modeling and simulating existing ones. Tests on actual use cases testified the effectiveness of the implemented approach.
Modelling Traffic Flow at Multi-Lane Urban Roundabouts
International Journal of Modern Physics C
This paper proposes Multi-stream Minimum Acceptable Space (MMAS) Cellular Automata (CA) models to study unsignalised multi-lane (two- or three-lane) urban roundabouts. Through detailed space considerations, using Cellular Automata (CA) and the Multi-stream Minimum Acceptable Space method, heterogeneity and inconsistency of driver behavior and interactions in cross traffic at entrances of roundabouts are simulated by incorporation of four different categories of driver behavior (i.e., conservative, moderate, urgent and radical), together with reassignment of categories with given probabilities at each time step. The method is able to reproduce many features of urban traffic, for which gap-acceptance models are not robust. Multi-lane roundabout models, in particular for two-lane roundabouts, are developed with different vehicle lane-allocation patterns. Various properties of multi-lane roundabout operations have been explored including throughput, turning rates, critical arrival rates...
A CELLULAR AUTOMATA MODEL FOR HIGHWAY TRAFFIC WITH PRELIMINARY RESULTS
2010
Cellular Automata are an established formal support for modelling traffic. STRATUNA is a Cellular Automata model for simulating two/three lanes highway traffic. It is based on an extensive specification of the driver response to the surrounding conditions. The model is deterministic with regard to driver behaviour, even if values of parameters ruling the reactivity level of the drivers are assigned stochastically. Probability distribution functions were deduced by field data and applied to vehicular flow generation (vehicle types, driver desired speed, entrance-exit gates). A partial implementation of STRATUNA was performed and applied to Italian highway A4 from Venice to Trieste. Simulations were compared with available field data with results that may be certainly considered encouraging in this initial implementation.
Cellular automata models of single-lane traffic
Physical Review E, 1997
The jamming transition in the stochastic cellular automaton model (Nagel-Schreckenberg model) of highway traffic is analyzed in detail, by studying the relaxation time, a mapping to surface growth problems and the investigation of correlation functions. Three different classes of behavior can be distinguished depending on the speed limit v max . For v max = 1 the model is closely related to KPZ class of surface growth. For 1 < v max < ∞ the relaxation time has a well defined peak at a density of cars ρ somewhat lower than position of the maximum in the fundamental diagram: This density can be identified with the jamming point. At the jamming point the properties of the correlations also change significantly. In the v max = ∞ limit the model undergoes a first order transition at ρ → 0. It seems that in the relevant cases 1 < v max < ∞ the jamming transition is under the influence of second order phase transition in the deterministic model and of the first order transition at v max = ∞.
A Model of City Traffic Based on Elementary Cellular Automata
2011
Several highway traffic models based on cellular automata have been proposed. The simplest one is elementary cellular automaton rule 184. We extend this model to city traffic with cellular automata coupled at intersections using only rules 184, 252, and 136. We study the model properties by simulating a single intersection. We describe the different dynamical phases of the model with velocity-density and flux-density diagrams. The model is useful for studying the problem of traffic light coordination for very large systems.
International Journal of Advanced Computer Science and Applications, 2012
In the real traffic situations, vehicle would make a braking as the response to avoid collision with another vehicle or avoid some obstacle like potholes, snow, or pedestrian that crosses the road unexpectedly. However, in some cases the spontaneous-braking may occur even though there are no obstacles in front of the vehicle. In some country, the reckless driving behaviors such as sudden-stop by public-buses, motorcycle which changing lane too quickly, or tailgating make the probability of braking getting increase. The new aspect of this paper is the simulation of braking behavior of the driver and presents the new Cellular Automata model for describing this characteristic. Moreover, this paper also examines the impact of lane-changing maneuvers to reduce the number of traffic congestion that caused by spontaneous-braking behavior of the vehicles.
A cellular automata based model for traffic in congested city
2009 IEEE International Conference on Systems, Man and Cybernetics, 2009
This work targets modeling traffic flow in roads of a congested city. The Cellular Automata (CA) have been configured for such modeling. The urban traffic models [2], in general, concentrate on low traffic density. The inabilities of traditional models to address the issues arise out of heavy traffic in crowded cities of third world countries are properly addressed in the proposed elementary CA based model. The effectiveness of the model is verified considering the traffic in Kolkata. It is established that the model can fairly reproduce various traffic conditions as found empirically. Further, the proposed model succeeds the limitations of traffic flow models in congestion and also reproduces the empirical results.