1,697 research outputs found
Wind effect analysis on air traffic congestion in terminal area via cellular automata
The behavior of any traffic flow is sensitive to the speed pattern of the vehicles involved. The heavier the traffic, the more sensitive the behavior is to speed changes. Focusing on air traffic flow, weather condition has a major role in the deviations of aircraft operational speed from the desired speed and causes surplus delays. In this paper, the effects of wind on delays in a terminal area are analyzed using a Cellular Automaton (CA) model. Cellular automata are discrete models that are widely used for simulating complex emerging properties of dynamic systems. A one-dimensional cellular array is used to model the flow of the terminal traffic into a wind field. The proposed model, due to the quickness and acceptable level of accuracy, can be utilized online in the tactical phase of air traffic control processes and system-level decision-makings, where quick response and system behavior are needed. The modeled route is an RNAV STAR route to Atlanta International Airport. The model is verified by real traffic data in a non-delayed scenario. Based on simulation results, the proposed model exhibits an acceptable level of accuracy (3–15% accuracy drop), with worthy time and computational efficiency (about 2.9 seconds run time for a 2-hour operation)
The effects of overtaking strategy in the Nagel-Schreckenberg model
Based on the Nagel-Schreckenberg (NS) model with periodic boundary
conditions, we proposed the NSOS model by adding the overtaking strategy (OS).
In our model, overtaking vehicles are randomly selected with probability at
each time step, and the successful overtaking is determined by their
velocities. We observed that (i) traffic jams still occur in the NSOS model;
(ii) OS increases the traffic flow in the regime where the densities exceed the
maximum flow density. We also studied the phase transition (from free flow
phase to jammed phase) of the NSOS model by analyzing the overtaking success
rate, order parameter, relaxation time and correlation function, respectively.
It was shown that the NSOS model differs from the NS model mainly in the jammed
regime, and the influence of OS on the transition density is dominated by the
braking probability Comment: 9 pages, 20 figures, to be published in The European Physical Journal
B (EPJB
Cellular Automata Models of Road Traffic
In this paper, we give an elaborate and understandable review of traffic
cellular automata (TCA) models, which are a class of computationally efficient
microscopic traffic flow models. TCA models arise from the physics discipline
of statistical mechanics, having the goal of reproducing the correct
macroscopic behaviour based on a minimal description of microscopic
interactions. After giving an overview of cellular automata (CA) models, their
background and physical setup, we introduce the mathematical notations, show
how to perform measurements on a TCA model's lattice of cells, as well as how
to convert these quantities into real-world units and vice versa. The majority
of this paper then relays an extensive account of the behavioural aspects of
several TCA models encountered in literature. Already, several reviews of TCA
models exist, but none of them consider all the models exclusively from the
behavioural point of view. In this respect, our overview fills this void, as it
focusses on the behaviour of the TCA models, by means of time-space and
phase-space diagrams, and histograms showing the distributions of vehicles'
speeds, space, and time gaps. In the report, we subsequently give a concise
overview of TCA models that are employed in a multi-lane setting, and some of
the TCA models used to describe city traffic as a two-dimensional grid of
cells, or as a road network with explicitly modelled intersections. The final
part of the paper illustrates some of the more common analytical approximations
to single-cell TCA models.Comment: Accepted for publication in "Physics Reports". A version of this
paper with high-quality images can be found at: http://phdsven.dyns.cx (go to
"Papers written"
A CA Hybrid of the Slow-to-Start and the Optimal Velocity Models and its Flow-Density Relation
The s2s-OVCA is a cellular automaton (CA) hybrid of the optimal velocity (OV)
model and the slow-to-start (s2s) model, which is introduced in the framework
of the ultradiscretization method. Inverse ultradiscretization as well as the
time continuous limit, which lead the s2s-OVCA to an integral-differential
equation, are presented. Several traffic phases such as a free flow as well as
slow flows corresponding to multiple metastable states are observed in the
flow-density relations of the s2s-OVCA. Based on the properties of the
stationary flow of the s2s-OVCA, the formulas for the flow-density relations
are derived
Non-concave fundamental diagrams and phase transitions in a stochastic traffic cellular automaton
Within the class of stochastic cellular automata models of traffic flows, we
look at the velocity dependent randomization variant (VDR-TCA) whose parameters
take on a specific set of extreme values. These initial conditions lead us to
the discovery of the emergence of four distinct phases. Studying the
transitions between these phases, allows us to establish a rigorous
classification based on their tempo-spatial behavioral characteristics. As a
result from the system's complex dynamics, its flow-density relation exhibits a
non-concave region in which forward propagating density waves are encountered.
All four phases furthermore share the common property that moving vehicles can
never increase their speed once the system has settled into an equilibrium
Prediction feedback in intelligent traffic systems
The optimal information feedback has a significant effect on many
socioeconomic systems like stock market and traffic systems aiming to make full
use of resources. In this paper, we studied dynamics of traffic flow with
real-time information provided and the influence of a feedback strategy named
prediction feedback strategy is introduced, based on a two-route scenario in
which dynamic information can be generated and displayed on the board to guide
road users to make a choice. Our model incorporates the effects of adaptability
into the cellular automaton models of traffic flow and simulation results
adopting this optimal information feedback strategy have demonstrated high
efficiency in controlling spatial distribution of traffic patterns compared
with the other three information feedback strategies, i.e., vehicle number and
flux.Comment: 14 pages, 15 figure
Effects of Prediction Feedback in Multi-Route Intelligent Traffic Systems
We first study the influence of an efficient feedback strategy named
prediction feedback strategy (PFS) based on a multi-route scenario in which
dynamic information can be generated and displayed on the board to guide road
users to make a choice. In this scenario, our model incorporates the effects of
adaptability into the cellular automaton models of traffic flow. Simulation
results adopting this optimal information feedback strategy have demonstrated
high efficiency in controlling spatial distribution of traffic patterns
compared with the other three information feedback strategies, i.e., vehicle
number and flux. At the end of this paper, we also discuss in what situation
PFS will become invalid in multi-route systems.Comment: 15 pages, 15 figures, Physica A (2010),
doi:10.1016/j.physa.2010.02.03
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