2nd International Conference on Urban Disaster Reduction
November 27~29, 2007

Study on Road Information Sharing Using Probe Vehicle in Disasters
N. KODAMA1*, Y. HADA1, T. SUZUKI1, I. SUETOMI2 and K. Meguro1
1

Institute of Industrial Science, The University of Tokyo, Japan
2

Japan Engineering Consultants Co., Ltd, Japan

Abstract
Road information sharing is vital in disaster response, but it still remains today a significant
problem in spite of the recent breakthrough of information and communication technology.
In this study, we overview the present situation and structure problems on road information
sharing. Two main problems are as follows: i) how to gather the information about whichroad can be used and ii) how to share the information among different disaster information
systems used in the authorities concerned.
We propose road information sharing using probe vehicle data to solve the first problem. The
characteristics and the possible use of the GIS plotted probe vehicle data in past disasters arediscussed. The probe vehicle data provide information to decide which road are likely toremain available at the time, and also where the vehicle turned around, that indicates the roadmight not be available.
The travel time of individual car trips are numerically simulated with and without roadinformation sharing among the cars. The reductions of the travel time depend on numbers ofprobe cars and road closures. The simulation results indicate that the probe vehicle data canbe effectively used to reduce the travel time in a time of disaster, and to gather regional
information on available roads.
Keyword: probe vehicle, road information, information sharing*

Corresponding author address: N. Kodama, The University of Tokyo, Japan, kodama@iis.u-tokyo.ac.jp

1. Introduction
Sharing traffic and road information is essential for effective disaster response. Despite therecent remarkable progress made in Information and Communication Technology, at present
there is no generally accepted solution for this problem.
Here we overview current state and problems in sharing traffic and road closure information.
We also propose and evaluate a new method for information sharing on road closure usingprobe vehicle data. Probe vehicles have been used practically in the transportation field [1] asa means of gathering information, such as speed and direction, from cars now driving.
2. Current state of information sharing during disasters
In this chapter, we overview schemes of road information sharing and contents of information
currently used. Most of the existing schemes are limited to major roads.
Ministry of Land, Infrastructure and Transport Government of Japan (MLIT) check damage
and availability of roads under the Ministry. Road information is provided through the internet
and electric bulletin boards installed above the roads. The tabular information provided in their
web site includes road closures and traffic regulation information of major roads.
Japan Road Traffic Information Center (JARTIC) [3] provides information gathering anddistribution services delegated from traffic administrators and roads authorities such as theNational Police Agency and MLIT. Traffic and road information is widely distributed throughradio, television and the internet. Tabular and graphical traffic information provided in their
web site includes route name, section and direction, cause and details of traffic regulation.
Vehicle Information and Communication System (VICS) [4] distributes literal and graphicaltraffic information to in-car navigation system. Drivers can get real-time traffic information,
including vehicle speed, travel time, accident, roadwork, speed limit, lane closure and carparks. About 70,000 km out of 330,000 km length of major roads are covered.
3. Problems in sharing traffic and road closure information
Road information of both disaster site and its surrounding areas is required for interregional
rescue and backup during disasters. This means that several road administrators are expected
to share their road information. We structure road information sharing problems during
disasters for road users and administrators through interview investigation.
3.1 Lifeline suppliers and physical distribution companies
1) It is difficult to exactly locate a position from literal road or traffic information.

2) They felt lack of information about road availability and damage severity.
3) They could not get well-timed road information while driving in the disaster site.
4) No special road information for emergency vehicles, which are given priority, is provided.
5) Reliability, update frequency and the last update time of information were not available.
6) Road information sharing and coordinated information providing are required.
3.2 Road administrators
1) Traffic regulation sections can not be exactly located, for their names are not standardized.
2) Regional road information which is required for finding a diversion is not shared.
3) Integrated road information service is not available during disasters.
4) Total length of local roads is so long that the administrator can not patrol in a short time.
5) An information system is required to gather road information from local residents anddrivers, and to share and provide it.
Lifeline suppliers and physical distribution companies
Unknown update frequency of road information

Slow to locate road information

Unknown reliability of road information

Literal traffic
regulation information

Not standardized names oftraffic regulation sections

No road information for
emergency vehicles

Slow to draw traffic regulation
information onto a map

No information on available roadNo information on damage severity

Road condition changes with time
Integrated road information
service not available

Road information published through individual platform
Difficult to integrate information in a system

Roads damaged simultaneously

Slow to grasp
available roads
Communicate by police radio

Limited information exchange

Road condition changes with time
Information from drivers not used

Difficult to input andbrowse information

Limited information disclosure
for security reasons

Slow to grasp road damage

Limited access to internet
for security reasons

Administrators become victimsCommunication blackout

Not manage road facilities
No origin for positioning specified

Traffic is not
the top priority

Local roads have long total length

Rescue and evacuation
are the highest priority

Roads damaged simultaneously
Reporting through facsimile and e-mailSlow to check local roads

GIS is not common

Many administrators fordifferent road types

Difficult to share information

Poor information sharing
among administrators
Police departments

Not standardized road information
Difficult to share information among systems

Road administrators

Fig. 1 Cause and effect diagram of road information sharing problems

3.3 Police departments
1) Traffic regulation information is gathered through facsimiles and e-mails whose forms
are not standardized. Traffic regulation sections are drawn onto a paper map afterwards.
2) High priorities are rescue operations, second disaster prevention and evacuation guidance
for which road information is vital.
Based on these interview results, road information sharing problems are structured in a cause
and effect diagram [5] shown in Fig. 1. The important points to share road information
effectively are as follows: 1) speedy check for road availability, 2) providing prompt access toroad information. Sharing probe vehicle data, which is explained in the following section, isproposed to solve the first problem described above.
4. Probe vehicle data and its effectivenessInformation on available roads is vital for effective disaster response, and it can be quickly
and directly gathered from probe vehicles. The vehicles record their position (longitude andlatitude), bearing, date and time.
4.1 Example of probe vehicle data in a disasterFig. 2 shows positions of probe vehicles every six hours from the occurrence of Niigata
Chuetsu earthquake, 2004 to the end of the next day. Short red lines mean road closures
which started by that time. Some vehicles have their trajectory records inside of the roadclosure sections. It occurred because the vehicles ran there before closed, or literal
information of road closure were interpreted longer than actual length on the map. Fig. 3
shows a trajectory of a vehicle turned around before road closures.
4.2 Simulation study of probe vehicle data sharing
We study here travel time and status known rate of available roads with and without roadinformation sharing. Status known rate is defined as a ratio of the length of roads at least one
probe vehicle passed over the total length of available roads. Road network of Niigata
Chuetsu region includes about 7,500 links and its total length is around 4,240 km.
Origin and destination pairs are randomly selected as their linear distances are around 50 km.
Average speed of vehicle assumed to be 30 km/h. The vehicles initially take the shortest pathto their destinations without road closure information. If they encounter a closed road, theyfind new shortest path from there to the destination. Road closure information is shared
among all the vehicles every five minutes. The probe vehicle data does not actually include

MotorwayNational road

05:32:35

Major street

05:32:19

Prefectural road
Other roads
Road closure
18-24, 23rd Oct.
0-6, 24th Oct.
6-12, 24th Oct.
12-18, 24th Oct.
18-24, 24th Oct.

05:30:19

05:27:19

Fig. 2 Probe vehicle trajectories after
Niigata Chuetsu earthquake, 2004
explicit road closure information, but it canbe derived from trajectories of vehicles
turned around.
Average travel time and status known rate ofStatus known rate of available roads

Fig. 3 Trajectory of a car turned
around before road closures
0.620cars (w)50cars （w）
100cars (w)

0.5
0.4
0.3
0.2
0.1
00

available roads for 100 cases were simulated
numerically with 20, 50, 100 vehicles and20cars (w/o)
50cars （w/o）
100cars (w/o)

200
400
Average travel time (min.)600

Fig. 4 Time variation of status known rateof available roads (300 closures)with random 100, 200, 300 road closures.
The average travel time and its shortening rate are shown in Table 1. The shortening rate isdefined as 1- (total travel time with information sharing)/(total travel time without information
sharing). Time variation of status known rate with 300 road closures is shown in Fig. 4.
Sharing road closure information shortened the maximum and the average travel time in allcases. Even in the case of 300 closures, information sharing among 100 probe cars brings morethan 12 % shortening of travel time. The information sharing of road closure reduces thenumber of trial times of shortest path search. This leads to smaller or larger status known ratecompared to that without information sharing, according to road network complexity. In caseof the road network of Niigata Chuetsu region, slightly larger status known rates wereobtained by road closure information sharing as shown in Table 2.
Sharing of probe vehicle data can achieve travel time shortening, as well as roadadministrators, lifeline suppliers and physical distribution companies can gather theinformation on the regional available roads of the disaster site.

Table 1 Average travel time and shortening rate of travel timeNum. ofroad
20closures w/o(min) w(min)
100
156.3
134.0
200
178.0
174.9
300
205.4
187.4

Number of vehicles
50100SR(%) w/o(min) w(min) SR(%) w/o(min) w(min)
14.3
167.8
141.1
15.9
161.3
138.9
1.7
189.8
170.9
10.0
178.0
155.6
8.8
201.4
187.1
7.1
194.9
171.2

SR(%)
13.9
12.6
12.2

w/o: travel time without information sharing, w: travel time with information sharing, SR: shortening rate

Table 2 Average status known rate of available roads
Number ofroad closures
100200300

20w/o(%)
15.9
16.9
18.0w(%)
16.5
18.0
19.4

Number of vehicles
50w/o(%)
w(%)
27.6
28.2
29.0
30.0
30.6
31.9100w/o(%)
w(%)
36.8
37.2
38.1
38.8
40.0
41.2

w/o: status known rate without information sharing, w: status known rate with information sharing

5. Conclusion
We overviewed problems in sharing traffic and road information during disasters from aninterview investigation, and structured them in a cause and effect diagram.
The important points to share road information effectively are as follows: 1) speedy check forroad availability, 2) providing prompt access to road information. We proposed probe vehicle
data sharing to solve the first problem described above. Actual probe vehicle data in a disaster
was introduced and its effectiveness in disaster response was shown.
Numerical simulations show that travel time can be shortened and information on available
roads in wide area can be gathered when road information derived from probe vehicle data isshared. The results shows that it is expected to work effectively in a large-scale disaster.
References[1] Road Bureau, The Ministry of Land, Infrastructure and Transport, "Monitoring of traffic

congestion - deployment of probe cars -", ITS Handbook Japan 2002-2003(http://www.its.go.jp/ITS/2002HBook/section4/4-9e.html).
[2] Disaster information provision center web site (http://www.bosaijoho.go.jp/, in Japanese)[3] Japan Road Traffic Information Center web site (http://www.jartic.or.jp/, in Japanese).
[4] Vehicle Information and Communication System Center web site(http://www.vics.or.jp/english/index.html).
[5] Ishikawa K., “Guide to Quality Control”, 2nd Revised Edition, Asian Productivity

Organization, (1986).