Modelling Traffic Flow at Multi-Lane Urban Roundabouts (original) (raw)
Related papers
A cellular automata model for urban traffic with multiple roundabouts
Chinese Journal of Physics
Urban transportation with multiple roundabouts is facing significant challenges such as traffic congestion, gridlock and traffic accidents. In order to understand these behaviors, we propose a two-dimensional cellular automata (CA) model, where all streets are two-way, with one lane in each direction. To allow the turning movement, a roundabout is designed for each intersection where four roads meet. The distance between each pair of roundabouts is configured with the parameter K while the turning behavior of drivers is modeled by a parameter γ. To study the impact of these different parameters on the urban traffic, several traffic metrics are considered such as traffic flow, average velocity, accident probability and waiting time at the entrance of roundabout. Our simulation results show that the urban traffic is in free flow state when the vehicle's density is low enough. However, when the density exceeds a critical density ρ c , the urban traffic will be in gridlock state whenever γ is nonzero. In the case where γ = 0, the urban traffic presents a phase transition between free flow and congested state. Furthermore, detailed analysis of the traffic metrics shows that the model parameters (γ, K) have a significant effects on urban traffic dynamics.
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.
Evaluating the performance of a multi-lane intersection is important to identify the best scheme as congestion is becoming a worldwide serious problem. A Multi-stream Minimum Acceptable Space (MMAS) Cellular Automata (CA) model is used for the simulation of vehicular traffic at double-lane roundabouts and cross intersection. Comparison is made between roundabouts with traffic light and without traffic light and signalized intersections on the basis of their performance to simplify traffic congestion. Computer simulations are used to propose critical arrival rates to separate between the three mentioned modes to decrease congestion at intersection points.
2013
Evaluating the performance of a multi-lane intersection is important to identify the best scheme as congestion is becoming a worldwide serious problem. A Multi-stream Minimum Acceptable Space (MMAS) Cellular Automata (CA) model is used for the simulation of vehicular traffic at double-lane roundabouts and cross intersection. Comparison is made between roundabouts with traffic light and without traffic light and signalized intersections on the basis of their performance to simplify traffic congestion. Computer simulations are used to propose critical arrival rates to separate between the three mentioned modes to decrease congestion at intersection points.
Effect of the lane reduction in the cellular automata models applied to the two-lane traffic
Physica A-statistical Mechanics and Its Applications, 2006
More investigated situations in the field of traffic modelling are those of traffic bottlenecks caused by slow vehicles or road defects. The new aspect of this paper is the simulation of vehicular dynamics near a partial reduction in a road from two lanes to one lane. In order to reduce the bad impact of waiting vehicles behind the defect region, a strategy regulating the vehicle movement in the vicinity of the reduced lane is taken into account. The simulation model is based on the cellular automata model of Nagel–Schreckenberg with additional rules of lane change. The partial lane reduction strongly reduces the road capacity, and the added regulation strategy leads to a more interesting shape of the fundamental diagram, which depends on different constraints on the model parameters, e.g., the length of the reduced lane, the maximal speed, and the length of the connection sites near the entry of the reduced lane.
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.
CELLULAR AUTOMATA MODELLING OF MULTILANE SIGNALIZED JUNCTIONS WITH HETEROGENEOUS TRAFFIC
Academia Letters, 2021
Intersections are an inevitable part of the road traffic system. If these are not designed properly, it can lead to several problems such as excessive delays, emissions and crashes. It is known that there are several points of conflict at the intersections that could cause crashes. Almost 49% of the total traffic crashes have been seen near intersections. Furthermore, studies also show that vehicle emissions are relatively higher during the acceleration or deceleration phase, which occurs at the intersections. It is difficult to understand traffic behaviour at the intersection as different activities, such as phase changes, multi-directional movements of vehicles, etc., occur at the same time. Proper intersection design can help to reduce delays, queues, emissions and crashes. Various models are used to understand traffic behaviour, such as microscopic, mesoscopic, and macroscopic models. Microscopic models consider traffic as individual driver-vehicles objects, whereas macroscopic traffic models analyze aggregated traffic. Mesoscopic models are hybrid of macroscopic and microscopic models. This study attempts to simulate the signalized intersections in a multi-lane heterogeneous traffic environment with a microscopic simulation approach. The simulation was done in order to understand the driver behaviour at the signalized junctions and to estimate the delays and emissions occurring at intersections. The simulation model developed in this research was built with the help of modified Cellular Automata (CA) rules in the MATLAB environment. This research consists of five parts: The first is the boundary selection of the simulation model. Second, the modelling of signalized intersections with multi-lane heterogeneous traffic. In the third part, the rules for cellular automaton near and away from the intersection were
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.
Analysis of Single-Lane and Two-Lane Traffic Models
The purpose of this paper is to extend the existing Cellular Automata (CA) models and to use the extended CA models to describe the influence of a car accident in single-lane and two-lane traffic flow. To evaluate dynamic traffic flow, we developed a traffic flow simulator that uses CA model. It is shown that the singlelane dynamics can be extended to the two-lane case without changing the basic properties of the model. The two-lane model considered here shows quantitative improvements over the single-lane model. We also add the lane changing rules to simulate the reality traffic condition. The spacetime diagrams for single and two-lane models are considered to conclude that congestion appear to move faster through traffic as the maximum velocity increases and congestion formation in single-lane is much distinct than in two-lane. Using simulation results it has been shown that after the accident the speed of the downstream traffic tends to zero which results in serious congestion and once the accident ends the traffic flow begins to start again.