22nd ITS World Congress, Bordeaux, France, 5–9 October 2015

Paper number ITS-2663

Simulation Experiment for ITS on Three Expressway Ringsin Tokyo Metropolitan Region
Ryota Horiguchi1*, Morihisa Iijima2, Takashi Oguchi3
1. i-Transport Lab. Co., Ltd., 3-10 Kanda-Ogawamachi, Chiyoda-ku, Tokyo, Japan,
Phone: +81-3-5283-8527, E-mail: rhoriguchi@i-transportlab.jp
2. i-Transport Lab. Co., Ltd., Japan
3. Institute of Industrial Science, University of Tokyo, Japan

Abstract
This paper describes traffic simulation studies for various traffic management schemes on theexpressway network in Tokyo metropolitan region. Preparing for the coming Olympic andParalympic Games in Tokyo 2020, three expressway rings around Tokyo are now close tocomplete forming web network. In order to mitigate congestions and to maintain smooth traffic,
there are many options for the traffic management such as travel information provision,congestion pricing, ramp metering, etc. To evaluate the effectiveness of those measures on alarge scale urban road network, we have developed a dynamic traffic simulation model'SOUND' which moves discrete vehicles according to the first ordered kinematic wave theory
and incorporates drivers' route choice behaviour. In this paper, let us outline our preliminary
study for the impact assessment of three expressway rings completion.
Keywords: traffic simulation, ring road network.
Introduction
This paper describes traffic simulation studies for various traffic management schemes on theexpressway network in Tokyo metropolitan region. Preparing for the coming Olympic andParalympic Games in Tokyo 2020, three expressway rings around Tokyo are now close tocomplete forming web network. Figure 1 illustrates the schematic structure of the expressway
network containing three rings closely completed and the years of their completion. The mostouter ring ‘Ken-ohdo’ surrounds Tokyo with a circle of which the radius is 40~50 km, while themiddle ring ‘Gaikan’ has approximately 25 km and the inner ring ‘MEX (MetropolitanExpressways) C2’ has 8~10 km in their radiuses. The blue sections of the ring roads are nowSimulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

under construction and will be open from 2015 to 2020.

圏央道
Ken‐odoGaikan外環道

MEX
首都高
中央環状C2Figure 1 – Expressway network in Tokyo Metropolitan Region
In order to mitigate congestions and to maintain smooth traffic by fully utilizing theperformance of those three rings, there are many options for the traffic management such as
travel information provision, congestion pricing, ramp metering, etc. To evaluate theeffectiveness of those measures on a large scale urban road network, we have developed adynamic traffic simulation model 'SOUND'1 which moves discrete vehicles according to thefirst ordered kinematic wave theory and incorporates dynamic drivers' route choice behaviour
considering traffic congestion, toll fare, travel information availability, and so on.
In this paper, the features of SOUND are briefly introduced at first. After the outline of the data
and the parameter settings for the simulation study, let us summarise our preliminary result todemonstrate the strategic pricing scheme to induce detouring traffic for the ring roads. In placeof conclusion, our future tasks will be discussed to propose efficient traffic management scheme.

Brief Introduction of SOUND – a Mesoscopic Network Traffic Simulation Model
SOUND (Simulation On Urban road Networks with Dynamic route choice) was originallydeveloped by the University of Tokyo and revised as a commercial software product2 by iTransport Lab. Co., Ltd. It is a mesoscopic traffic simulation model which moves discrete
vehicles second by second according to the fundamental diagram of traffic flow. The vehicles
running on a link are treated in a physical queue which can reproduce shockwave propagation
by implementing the simplified kinematic wave algorithm (K-wave) proposed by Newell3. As
the computational cost of K-wave is much lighter than of car following model which update2

Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

vehicles’ positions and speeds in sub-second, SOUND has an advantage to other microscopic
traffic simulators for the applicability to large scale road networks.
As for the drivers’ behaviour modelling, SOUND incorporates stochastic route choice modelwith dynamic user optimal (DUO) principle. It implements Dial’s assignment algorithm4 to
avoid time-consuming path enumeration process and can revise the route choice probability forevery interval normally designated as 5 – 15 minutes to ensure the modelling capability ofvarious ITS measures.
Simulation Study with the Tokyo Metropolitan Road NetworkBy using SOUND, we have conducted the preliminary simulation study to assess the impact of
the completion of three expressway rings. Figure 2 shows the study network containing both
expressways with blue lines and arterial roads with other colours. The network spreads over theTokyo Metropolitan Region and surrounding prefectures with approximately 200 x 200 km2
area and contains approximately 186K nodes and 410K directional links. In the preliminary
study, let us assign the default capacity to each link according to the limit speed and the numberof lanes.

Figure 2 – the study network over the Tokyo Metropolitan Region and surrounding
prefectures
Figure 3 shows the zones of which number is 1,112 used for the O-D investigation in the traffic
census conducted by the Ministry of Land use, Infrastructure and Transportation (MLIT). For3

Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

this region, MLIT aggregates the result of O-D investigation and provides daily traffic demand(the census O-D matrix) of which total trip generation is approximately 26,775K vehicles perday, whereas dynamic traffic simulation requires time-dependent O-D matrix. In thepreliminary study, let us simply divide the census O-D matrix with the departure time profiles
according to the vehicle type and the direct direction from origin zone centre to destination zone
centre, as shown in Figure 4. Here, the ‘inbound’ represents the direction towards the emperor
palace in the centre of Tokyo.

Figure 3 – the zones used by the O-D matrix (census B-zones)

Departure time profiles
車種別・方向別時間係数
Relative frequency
各時刻における日交通量に対する割合

0.07
0.06
0.05
0.04
0.03
0.02
0.01
04AM

8AM

PC‐outbound小型：下り

HV‐outbound
大型：下り0PM

4PM

PC‐inbound
小型：上り

HV‐inbound
大型：上り8PM0AM

PC‐other
小型：環状HV‐other大型：環状Figure 4 – the departure time profiles
As for the route choice model parameters, let us follow the conventional settings5 as follows;4Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Regionc = 0.5D/VE + 0.5T + 30NL + 60NR + 0.67F
where c:generic cost from a link to a destination
D:
distance to the destination [m]VE:expected travel speed from statistics [m/sec]T:present travel time reproduced in the simulation [sec]NL:number of left turnsNR:
number of right turns
F:toll fare [yen]In this case, all generic costs are updated for every 5 minutes.

Simulation Studies
Present case
Figure 5 shows the daily traffic volume of each link in the result of the ‘present’ case, which
gives the baseline of the study. The calculation time takes almost 30 hours by using the Intel
Corei7-3820 CPU with 64GB RAM.
Future case after the three rings completion
Figure 6 shows the differences in daily traffic volume after the three rings completion. It is
normally expected that any impacts of the network completion can be positive and preferable
to reduce congestion, however it is sometimes happen to induce unexpected congestions atdifferent places. In this case, the new congestion will be arise by heading to the new junctions
at the crossing points of the Ken’odo and the Gaikan-do with the radial expressways.
Strategic Pricing with ‘toll-free’ Ken’odo
Figure 7 shows the differences in daily traffic volume if the toll fare of the Ken’odo sets to free.
In this case, some accessing sections to the Ken’odo increase their traffic, but most of the inner
Ken’odo links reduces traffic. It is expected that the congestion in the Tokyo city centre will bemitigated.

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Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

Figure 5 – the daily traffic volume of each link for the present case

Figure 6 – the differences in daily traffic volume after the three rings completion

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Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

Figure 7 – the differences in daily traffic volume for the toll-free Ken’odo case
Future Works
The preliminary studies described above were conducted to demonstrate the assessment using
dynamic traffic simulation. We also need to calibrate the link parameters to reproduce traffic
congestion properly. The route choice model parameters are to be identified though the analysisof probe car data. For the further study, more dynamic ITS measures, such as dynamic roadpricing, predictable traffic information provision, variable shoulder lane use, etc. are to bemodelled and implemented in SOUND.
References
1. Yoshii, T. Kuwahara, M. (1995). SOUND: A Traffic Simulation Model for Oversaturated
Traffic Flow on Urban Expressways, Preprint at 7th World Conference on Transportation
Research, Sydney.
2. SOUND product page (visited in July 2015). http://www.i-transportlab.jp/product/sound(in Japanese).
3. Newell, G. F. (1993). A simplified theory of kinematic waves in highway traffic, Part I:
General theory, Transportation. Res.-B, Vol. 278, No. 4, pp. 281-287.
4. Dial, R. B. (1971). A Probabilistic Multipath Traffic Assignment Algorithm Which Obviates
Path Enumeration. Transportation Research 5, pp. 83-111.

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Simulation Experiment for ITS on Three Expressway Rings in Tokyo Metropolitan Region

5. Tamamoto, G. Horiguchi, R. Kuwahara, M. (2004). Application of Traffic Simulation
SOUND to the Large Network, Proceedings of 30th Infrastructure Planning (in Japanese).
6. Hanabusa, H. Shiraishi, T. Koide, K. Horiguchi, R. (2011). Development of a Hybrid Traffic
Simulation Framework for Environmental Evaluation for ITS Applications, Proceedings ofthe 18th World Congress on Intelligent Transport Systems, Orlando.
7. Horiguchi, R. Hanabusa, H. Kuwahara, M. Tanaka, S. Oguchi, T. Oneyama, H. Hirai, H.
Hayashi, S. (2010). Validation Scheme for Traffic Simulation to Estimate EnvironmentalImpact 'Energy-ITS Project', Proceedings of 17th World Congress on Intelligent Transport
Systems, Busan, Korea.

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