Information and Communication Technology Seminar, Vol. 1 No. 1, August 2005
ISSN 1858-1633 2005 ICTS 151
A SIMPLE QUEUING SYSTEM TO MODEL THE TRAFFIC FLOW AT THE TOLL-GATE: PRELIMINARY RESULTS
Wahju Sediono, Dwi Handoko
Center for the Assessment and Application of Information Technology and Electronics P3TIE-BPPT Communication and Computation Technology Division
BPPT Building II 4th Fl., Jl. M. H. Thamrin No. 8, Jakarta 10340 E-mail: sedionoyahoo.com, dwihinn.bppt.go.id
ABSTRACT
Nowadays traffic jam can be found anywhere at anytime. A well planned traffic rules can decrease the
traffic jam. In order to support traffic rules planning, a simulation tool is currently developed in our division.
In this paper a traffic simulator tool based on a simple queuing system, which can be effectively applied to
model traffic conditions at the highway toll-gate, is introduced. By using this tool we can make
performance tests on a real toll-gate which are based on various traffic flows and other parameter values. In
the near future this software tool can be used to optimize the operations of the existing toll-gates or
predict the traffic situations on the next planned toll- gates.
Keywords: traffic simulator, simple queuing system, traffic flow
1. INTRODUCTION
Traffic jams and crowded situations on the streets, especially in big cities, are believed to cause negative
effects on both the environment and human being. In a jam situation the vehicles can move forward slowly so
that a large amount of unhealthy gas produced on a certain area at a certain time can raise non-negligible
air pollution. At the same time the traffic’s noise can also be a source of serious ecological damage. It is
understandable if these discomforts can additionally increase the stress of people trapped in the jam and of
them who live around. In a long term this traffic conditions are believed to decrease the productivity of
a nation.
An important reason for the traffic jam is the unbalance between the traffic flow and the street
capacity. Well planned traffic rules can be used to control the traffic flow so that the overcapacity of the
streets should never happen. To support in planning the traffic rules a software tool is currently developed
in our division. The goal of this work is to get an appropriate traffic model that can be easily applied on
the real existing traffic situations. By using this software tool an impact of the next planned traffic
rules can be simulated on a computer model before the final realization [1][2].
As a step of reaching our goal we have developed a simple queuing system to model the traffic flow at
the toll-gate, as a part of the grand design of the traffic simulator. In this paper preliminary results of the
simulation based on this model are presented.
2. A SIMPLE MODEL OF THE QUEUING SYSTEM
Because of its simplicity the traffic condition at the toll-gate is chosen as a special case in doing
performance tests on the developed traffic simulator. A typical highway with a series of toll-gates is shown
in figure 1.
Basically the vehicle queues at the toll-gate can be modeled by a simple queuing system. The
characteristics of this queuing model are described by the queue’s length or capacity, the arrival’s rate of the
traffic and the processing time in the toll-gate [3][4].
Fig 1: A highway with a series of toll-gates that can be modeled by a simple queuing system
In case of the traffic at the toll-gate the lengths of the queues at a certain time are determined by various
factors like the road’s physical condition, the measurement time, the driver’s behavior, the gate’s
capacity and the existing traffic flow. A bad condition of the toll road or a lane shrinking could raise a long
queue in a short time. A bad maintained car can make the traffic flow get slower, so that a not-freely queue
exists. And, frequently, long queues are also produced by the undisciplined drivers as they are involved in
accidents.
The arrival’s rates of the vehicles at the toll-road are mainly driven by the measurement time. At busy
hours we can expect a high rate of the vehicle’s arrival
Information and Communication Technology Seminar, Vol. 1 No. 1, August 2005
ISSN 1858-1633 2005 ICTS 152
towards the inner city’s highway, whereas a slow rate is usually expected e.g. in the very early morning or at
holidays. The processing time determine how long a vehicle
would stay in the queue. In case of the vehicle queue at the toll-gate this processing time is dependent on
the speed of the processing machine or people handling the vehicle’s arrival and the reliability of the
supporting software behind.
Fig 2: A model of simple queuing system
However in this step we don’t take into account all of those parameters. In this development step, to
simplify the problem of modeling only the arrival’s rate r of the vehicle is used to determine the traffic
flow in this paper. The characteristics of the queues are described by the parameters l for the queue’s
length and t for the processing time fig. 2. However this model is also provided to model a more complex
queuing system which is characterized by the lanes m before the gate, the lanes g in the gate and the lanes n
after the gate [5]. Therefore our model of simple queuing system is determined by parameters of r, l, t,
m
, n, and g.
Fig 3: The very simple graphical user interface of the software tool
Basically, by using the appropriate data structure and algorithms, we can simulate the vehicle queues at
the toll-gate on the computer. The independent appearance of the vehicles in the queues is realized by
using the principles of the object-oriented method. To get an easy run of the software tool a simple user
interface is of great importance. A very simple graphical user interface is shown in fig. 3.
3. SIMULATION RESULTS
