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Hindawi Publishing CorporationDiscrete Dynamics in Nature and
SocietyVolume 2013, Article ID 234970, 2
pageshttp://dx.doi.org/10.1155/2013/234970
EditorialDiscrete Dynamics in Transportation System
Wuhong Wang,1 Klaus Bengler,2 and Geert Wets3
1 Department of Transportation Engineering, Beijing Institute of
Technology, Beijing 100081, China2 Lehrstuhl für Ergonomie,
Technische Universität München, 85747 Munich, Germany3
Transportation Research Institute (IMOB), Hasselt University, 3590
Diepenbeek, Belgium
Correspondence should be addressed to Wuhong Wang;
[email protected]
Received 24 October 2012; Accepted 31 October 2012
Copyright © 2013 Wuhong Wang et al.This is an open access
article distributed under the Creative Commons Attribution
License,which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly
cited.
1. Overview
A transportation system is a dynamic, diverse, randomand complex
system, which consists of road users, vehicles,roadway, and the
environment. An efficient transportationsystem is essential for the
function and prosperity of modern,industrialized societies, and any
disturbance of the compo-nents will transform the state of the
whole system.
A transportation system exhibits extremely complexbehavior
derived from several components: the heteroge-neous nature of human
behavior, highly nonlinear groupdynamics, and large system
dimensions. Advances in mobil-ity aremost clearly illustrated by
the spread ofmotorized traf-fic and transport and the development
of the transportationindustry, including vehicle manufacturing and
its associatedinfrastructure. However, because of the growth of the
trans-portation system, it also shows some negative impacts suchas
the increasing number of traffic accidents, the danger ofhealth
problems due to pollution, and the possibility of eco-nomical
drawbacks due to congestion problems. Therefore,to reduce these
negative impacts, the current developmentsin the transportation
system represent one of the mainchallenges for information science
and intelligent technology.
In order to reach a more efficient and safe road usage,some
innovative techniques are performing in a transporta-tion system,
for example, intelligent transportation system(ITS). ITS includes a
wide and growing suite of technolo-gies and applications, aiming at
providing available servicesrelating to different modes of
transportation and trafficmanagement and enabling various users to
make safer, morecoordinated, and “smarter,” use of transportation
system.The whole techniques of ITS can be divided into two
parts:
stand-alone systems and cooperative systems. The two kindsof
systems should work together to deliver the most efficient,safe,
secure and comfortable journey.
To tackle the problems that were introduced before, trafficon an
urban transportation system can be considered as adynamical system.
In recent years, some researches based onchaos theory were used to
describe the traffic flow. Nonlinearchaotic phenomena was found in
the short-term traffic flows,and even some implications were
discussed for urban andtransportation planning and forecasting.
Period doubling,intermittency, and quasiperiodicity would make the
trans-portation system into chaotic. The chaotic traffic flow
modelis a macroscopic model, which was established by adoptingcar
following model. The model is a discrete and dynamicone derived
from both the flow-density-speed fundamentaldiagram and the
Greenshield’s model, which use occupancyas variable and the ratio
of free flow and average speed as con-trol parameter.
With the development of society, the transport systemshows a
high complex and variational scene and enormousstochasticity.
Various transportation problems and activities,such as accidents,
unreasonable control signal, and tem-porary society actives, are
derived from nonlinear singularfactors which are the main causes of
the stochasticity. Thisstochasticity can be defined as the
impedance of the path.Consequently, the problem proposed how to
find out theexpected shortest path in a transport network, where
thelink travel times are modeled as a continuous-time
stochasticprocess. The famous approaches for solving the problem
arethe Bellman’s dynamic programming method for directednetworks,
the Dijkstra labeling method, and Bellman-Ford successive
approximation method for networks with
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2 Discrete Dynamics in Nature and Society
nonnegative cost coefficients. Some important applicationsof the
path optimization problem include vehicle routingin transportation
systems, traffic routing in communicationnetworks, and path
planning in robotic systems.
Discrete optimization is a specific branch of optimizationin
applied mathematics and computer science. A very well-known
application area of discrete optimization is a railtransport
system. It helps us to plan and optimize the railroadnetwork, in
particular, the computation of the line plans, trainschedules, and
schedules of rolling stock. For example, theline planning consists
in choosing a set of operating lines andits frequencies to serve
the passenger demand and to optimizesome given objective. However,
the process of privatization ofstate-owned railroads enforces the
efficient resource utiliza-tion. For this reason, cost-optimal line
planning is modeled.Besides the routes and the frequencies, in the
cost-optimalline planning approach, one has to find the optimal
number ofcoaches per train, based on trivial estimates of the
circulationof rolling stock.
To solve problems of a transportation system, next to
opti-mization also human behavior plays a crucial role.
Amongvarious disturbances of transportation system, the
reliabilityof human action in transportation system plays a
crucialrole in optimizing both person-task fit and safety
issues.According to the result of all investigations over the
world,accidents are to be led back to more than 95% exclusively
onthe driver’s behavior. Disturbances such as human error canmake
the transportation system into a variety of unreliablestate. On the
basis of the measuring system disturbances, theunstable state can
be defined as varying degrees of safety, suchas conflict, near
accident, or accident. Certainly, an unreliabletransportation
system can also transform into a reliable stateby compensate
strategies in safety efforts. The advanceddriver assistance systems
(ADASs) is such a subsystem ofITS, which helps drivers in
perception, decision making, andaction while driving and enhances
the possibility of humanerror compensation, such as collision
warning systems, lanedeparture warning systems, adaptive cruise
control system(ACC), vision enhancement, and pedestrian
detection.
The focus of this special issue is to foster links betweenbasic
and applied research relating to discrete dynamicsproblems in a
transportation system. We invite original con-tributions on all
topics in both new theoretical developmentsand studies of practical
implementations, which propose andstudy novel dynamic and diverse
models to reveal the mech-anism of transportation system.The topics
include intelligenttransportation system (ITS), dynamic problem in
urbantransport system, transit and rail systems operation,
applica-tion of chaos in traffic flow, discrete and stochastic
theory oftransport system, vehicle active safety and intelligent
vehicle,discrete optimizationmethods in traffic system, traffic
opera-tions, management and control, energy, transport policy
andeconomics, driving behavior, and driver assistance system.
2. Summary
An efficient and safe transportation system is essential forthe
function and prosperity of modern society. Nowadays,we have
benefited from the rapid development of the
transportation industry. However, we also have to sufferfrom
serious problems in transportation. Therefore, manyresearchers are
seeking solutions to make a transportationsystem more efficient and
improve the operations by usingnew technologies and new
methodologies.
The analyzing, testing, modeling, and simulating of
atransportation system and the state-of-the-art technologieswill
collectively improve the accidents, congestion, and pol-lution
emissions problem of the transportation system.
This special issue aims at understanding the discretestate
modeling the dynamic changes of the transportationsystem and
finding a more reliable compensating approachto enhance the safety
and efficiency of the transportationsystem.Webelieve that the
papers in the special issue could bea representative study in the
field of intelligent transportationsystem and help for a heuristic
understanding of the currentdevelopment in the field of
transportation safety.
Wuhong WangKlaus Bengler
Geert Wets
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