A Development of Traffic Prediction System
Based on Real-time Simulation

Tomoyoshi SHIRAISHI
Researcher, Center for Collaborative Research, University of Tokyo

B206, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8904 Japan
Phone:+81-3-5452-6565, Fax: +81-3-5452-6800,
E-mail :shiraisi@iis.u-tokyo.ac.jp
Masao KUWAHARA
Professor, Institute of Industrial Science, University of Tokyo

Cw-504, 4-6-1 Komaba, Meguro-ku, Tokyo, 153-8505 Japan
Phone:+81-3-5452-6419, Fax: +81-3-5452-6420,
E-mail : kuwahara@iis.u-tokyo.ac.jp
Ryota HORIGUCHI
Representative Manager, i-Transport Lab. Co., Ltd.

2-12-404 Ageba-cho, Shinjuku-ku, Tokyo 162-0824 Japan
Pahone/Fax:+81-3-5261-3077,
E-mail: horiguchi@i-transportlab.jp

ABSTRACTThe purpose of this research is to develop a traffic prediction system by using the real-time
information (vehicle detector, VICS etc) and the existent traffic simulation. It is to watch
conditions to change with the time always and to hold traffic control suitably. Recently, atraffic jam happens chronically frequently, and it is a big social problem in the urban
expressway. To control this traffic safely and smoothly, it is important to give a plan more
rapidly and suitably. We think that this system is useful as an examination and evaluation toolof the policy by predicting future short-term traffic conditions from the present trafficconditions.
1. INTRODUCTION
Recently, chronic traffic jam often happens at the urban expressway in Japan. So, it is a big
social problem. To control the traffic-flow safely and smoothly, it is important to take more

rapid and suitable measures. In this research, we developed a traffic prediction system basedon the real-time simulation.
"Real-time simulation" is the system that using the real-time information such as a vehicles
sensor and VICS always reproduces the present condition.
This traffic prediction system is a tool that predicts future short-term traffic conditions withestimating inflow traffic quantity to the network based on the present condition reproduced bythis real-time simulation.
We think that road control service at the urban expressway can be supported by using thissystem.
2. REAL-TIME PREDICTION SYSTEM
A real-time prediction system in this research has the following features.
This system acquires new information from the vehicle detectors and so on connected on-line
and guesses present traffic condition.
This system rebuilds the present traffic condition that it guesses on the simulation, andpredicts near future traffic conditions from that time.
Furthermore, the system has the following features to realize these.
"The OD ratio" of the vehicles that exist on the link in the prediction start time is estimated byusing "the real-time simulation" which moves vehicles in accordance with a change in link
trip time until that time of that day in this system. And, this system guesses present traffic
conditions from "the OD ratio", and it has a "HOT START" function to read in "the prediction
simulation" in the prediction start time.
A system has the "OD traffic prediction" function that time series predicts OD traffic quantitythat it flows in to the network until a future moment to predict from the prediction startmoment. The simulation models uses "SOUND (Simulation On Urban road Network with
Dynamic route guidance)1),2).

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3. FRAMEWORK OF THE PREDICTION SYSTEM

Fig. 1

Framework

The framework of the real-time prediction system is shown in Fig.1. It supposes that real-time
information from the vehicle sensor is acquired in the interval of 5 minutes. The real-time
simulation is initialized from before by 4 hours in the estimate opening time, and works
real-time after the simulation time reaches the actual present time. When predicting, thepresent traffic condition is created by the hot start and is loaded in the prediction simulation as
the input data of the simulation.
When the present is estimated by another simulation when executing a hot start, this systemjudges whether or not to start up an estimate simulation newly about whether it extends
estimate by the estrangement of existing simulation and the traffic status which was createdby the hot start.
a. Real-time Simulation
In the prediction system, the destination information of the individual vehicle that exists on
the link is necessary. But, this can’t be gotten from the real-time information. The real-time
simulation estimates the destination information of Individual vehicle (Fig.2).

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Fig. 2

Real-time Simulationb. Prediction Simulation
The prediction simulation is the function to predict traffic condition to the time in the future towant to estimate from the traffic status at the time of the prediction start. The prediction
simulation is composed “Hot-Start” and “OD traffic quantity prediction”.
Hot-Start

Fig. 3

Hot Start data flow4

“Hot-Start” extends to suit actual traffic condition that can get from the real-time information
and “the OD ratio” which is the output of the real-time simulation, and allocates destination
information for each vehicle that exists at each link(Fig.3).
OD traffic quantity prediction“OD traffic quantity prediction” is the function to predict the OD traffic that flows in to thenetwork to the time in the future to want to predict from the prediction start time in the timeseries. It uses an average traffic quantity pattern and AR model in the past for the predictionof the OD traffic quantity (Fig.4).

X t = φ1 X t −1 + ... + φ p X t − p + Z t
t = 0,±1,...
Fig. 4prediction equation (AR-model)

The case that estimated traffic using this technique is shown in the fig.5.

Fig. 5 The case that estimated traffic using AR Model and Average Pattern5The following figure shows the data flow on the prediction system (Fig.6).

Fig. 6

Presiction system data flow

4. Future WorksAfter system building is completed, we will try system verification.
System verification is carried out in the all of MEX(Fig.7).
・ Entire length: 283.3km
・ Number of links to use for the simulation: 1388 Links・ Points: 368Points
And, the standard OD table was made based on the investigation that MEX carried it out.

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Fig. 7 Network for the system verification (All MEX roads)

REFERENCES[1]

Mineo YOSHII, Masao KUWAHARA, Hirohisa MORITA ： ”TOSHI-NAI
KOUSOKU-DOURO NI OKERU KAHOUWA NETWORK SIMULATION MODEL NO
KAIHATSU”, Traffic Engineering，Vol.30，No.1, 1995

[2]

SOUND product information: http://www.i-transportlab.jp/products/sound[3]

Gakuya TAMAMOTO, Masao KUWAHARA, Ryota HORIGUCHI, Edward CHUNG,Shinji TANAKA, Kou SATOU and Tomoyoshi SHIRAISHI ： Application of Traffic
Simulation SOUND to the Tokyo Metropolitan Network , Proceedings of 11th World
Congress on Intelligent Transport Systems，Nagoya， 2004.10[4]

Tomoyoshi Shiraishi，Masao Kuwahara，Ryota Horiguchi;Tomoyoshi Shiraishi，Masao
Kuwahara，Ryota Horiguchi; A Development of Traffic Prediction System Based on
Real-time Simulation, Conference of Infrastructure Planning Proceedings Vol.30,
CD-ROM, 2004

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