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9Статья поступила в редакцию 12.08.2010. Ред. рег. № 851
The article has entered in publishing office 12.08.2010. Ed. reg. No. 851
DEVELOPMENT OF SUPER-HIGH DENSITY TRAFFIC INFORMATION SYSTEM USING PROBE INFORMATION
K. Satou, T. Nakajima, K. Ohnuki
NISSAN MOTOR CO., LTD.
1-1, Aoyama, Morinosato, Atsugi-shi, Kanagawa, 243-0123, Japan Tel: +81-46-290-0823, FAX: +81-46-290-0964
Nissan installed the "Fastest Route Guidance" function in a navigation using telematics in 2004 on FUGA. This function is a service to provide fastest route and accurate expected arrival time by searching the route from traffic information. Moreover, the improvement of Fastest Route Guidance performance was achieved by installing "Probe traffic information" function to generate traffic information based on running tracks data collected from vehicles in the navigation installed on SKYLINE from 2006. Latest navigation from 2009 expanded the road information greatly by receiving probe traffic information and by reflecting intersection information according to the right turn and left turn cases.
СОЗДАНИЕ ИНФОРМАЦИОННОЙ СИСТЕМЫ ДЛЯ ОЦЕНКИ ДОРОЖНЫХ ЗАТОРОВ ПО ДАННЫМ, ПОЛУЧЕННЫМ ОТ АВТОМОБИЛЕЙ-УЧАСТНИКОВ ДОРОЖНОГО ДВИЖЕНИЯ
К. Сато, Т. Накаджима, К. Онуки
В 2004 г. в телеинформационную навигационную систему на автомобилях FUGA была добавлена функция определения оптимального маршрута пути по минимальному времени (Fastest Route Guidance). Данная функция служит для обеспечения минимального времени в пути и максимально точного времени прибытия в место назначения благодаря выбору маршрута на основании данных об интенсивности движения. Затем для повышения эффективности системы Fastest Route Guidance была внедрена функция зондирования интенсивности движения, которая генерирует отчеты об интенсивности движения по данным о маршрутах, собираемым от автомобилей в системе навигации, устанавливаемой на модели SKYLINE с 2006 г. В последней версии навигационной системы, появившейся в 2009 г., спектр дорожной информации был значительно расширен благодаря получению данных зондирования интенсивности движения и учету данных пересечения перекрестков при поворотах направо и налево.
Kouji Satou
Organization(s): Electronics Engineering Development Division, IT and ITS Engineering Department, IT/Telematics Advanced Engineering Group, Manager.
Main range of scientific interests: Telematics Engineering, Navigation system.
Organization(s): Electronics Engineering Development Division, IT and ITS Engineering Department, IT/Telematics Advanced Engineering Group.
Main range of scientific interests: Telematics Engineering, Navigation system.
Organization(s): Electronics Engineering Development Division, IT and ITS Engineering Department, IT/Telematics Design Group.
Main range of scientific interests: Telematics Engineering, Navigation system.
Toshiharu Nakajima
Kazutoshi Ohnuki
1. Introduction
Nissan has started the "Fastest Route Guidance" service in a navigation system equipped on FUGA released in 2004. This service provides the driver with the fastest route for minimizing travel time and accurate expected arrival time by using both latest and statistic traffic information. The latest traffic information is received from CARWINGS center via mobile phones to provide unexpected traffic congestion. The statistic traffic information processed by the past traffic information is pre-installed into the on-board navigation system to provide daily traffic information.
The above traffic information delivered from CARWINGS center is VICS (Vehicle Information and Communication System) information, which is generated by JARTIC (Japan Road Traffic Information Center) and VICS center on the basis of the traffic flow data collected from sensors on major roads. Sensors such as vehicle detectors need to be installed on the road to generate the said VICS information. Therefore, road infrastructure will be developed on a priority beginning with major roads. Presently, road coverage in which traffic information is provided remains approximately 10% out of all roads where the on-board navigation system can provide route guidance (roads of route guidance).
Navigation systems, which have been sequentially, equipped from SKYLINE, released in 2006, "Probe Traffic Information" service begun to increase the road coverage rate of traffic information. In this "Probe Traffic Information" service, vehicle information (called as "Probe information" hereinafter) such as actual driving tracks of CARWINGS users are collected via a mobile
phone by CARWINGS center and processed into traffic information so as to deliver the traffic information to the roads not covered by VICS information.
In the latest navigation systems released in 2009 which is stated in this paper, two technologies were developed as follows further utilizing probe information collected from vehicles.
• Expand the number of roads where probe traffic information is delivered
• Provide traffic information according to right/ left turn at intersection
This paper refers to the above technologies.
2. Former "Fastest Route Guidance"
2.1 Function overview of "Fastest Route Guidance" To provide "Fastest Route Guidance" in which a navigation system provides with the fastest route and high accuracy expected arrival time, information on the travel time for every potential road where the vehicle may pass during the driving from the present location to the destination is needed. Therefore, the accuracy of the travel time for each potential road has a significant impact on the fastest route guidance performance. This travel time is not constant but varies from hour to hour depending on the road congestion level etc. It is necessary to take into account the traffic situation of each road to calculate the accurate travel time.
For calculating the travel time for each road, the 2006 model of navigation system uses the traffic information as shown in the following Table.
List of road category and variation of traffic information
Road types Traffic information to be used Method of information delivery
Roads guidable by a navigation system VICS defined links Links providing VICS information VICS information, and traffic information estimated based on the VICS information Deliver the information in real time from CARWINGS center
Links not providing VICS information Probe traffic information
VICS not-defined links Links providing statistic traffic information Pre-installed into the onboard navigation system
"VICS defined links" means the links managed by VICS center by assigning an ID for each road to deliver traffic information "VICS not-defined links" means the links other than VICS defined links in all roads guidable by a navigation systm "Links providing VICS information" means the links of all VICS defined links, which are actually provided with VICS information "Links not providing VICS information" means the links of all VICS defined links, which are actually not provided with VICS information
International Scientific Journal for Alternative Energy and Ecology № 9 (89) 2010
© Scientific Technical Centre «TATA», 2010
In order to deliver the traffic information from CARWINGS center to the on-board navigation system, both CARWINGS center and navigation system need to have common road number information (called as "Road link ID" hereinafter). For instance, if CARWINGS center delivers the traffic information of road A as road link ID=1, the navigation system also needs to identify the received road link ID=1 as road A. As explained above, it is necessary to assign road link ID to each road for providing the traffic information.
This 2006 model of navigation system diverts the VICS link ID that is generally defined for navigation
system by VICS center to the road link ID. The road link ID delivers real-time traffic information via CARWINGS center. The use of this VICS link ID will reduce the development period without the need for defining an independent link ID. Additionally, of all VICS defined links, links not provided by VICS information can increase the road coverage rate of traffic information from 10% to 50% by means of the probe traffic information generated by CARWINGS center based on probe information of CARWINGS user's driving tracks (See Fig. 1).
VICS defined links Links provided 47%
Links actually provided with information from VICS center
Fig. 1. Traffic information cover rate of 2006 model (100% as for the roads of the route guidance)
2.2 Transition of improvement in performance of "Fastest Route Guidance" Fig. 2 below shows the transition of improvement in performance of the former fastest route guidance. Given that the navigation systems before installing this function is used as criteria, travel time was reduced by more than 10% and the error tolerance of expected arrival time was improved from 40% to 10% (Accuracy improvement by 75%).
e
e at
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oi ti
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-5
Tolerance of expected arrival time [% 10 15 20 25 30 35
The 2004 model
The 2006 model Fastest Route using VICS and Probe informal
(Based o
J ¡astest Roi ite using
n the test re
ults by usin
e function)
'ICS infor nation only
ion
g the routes
specified by Nissan)
More accurate expected arrival time
Fig. 2. Transition of performance gain of former model
2.3 Challenges of the former "Fastest Route Guidance"
Compared to the former navigation systems, which provide only VICS information, the 2006 model of navigation system dramatically improved the road coverage rate of traffic information. On the other hand, road link ID has the following challenges as it uses the VICS link ID that is defined by VICS center.
(1) VICS defined links are subject to the delivery of traffic information. Therefore, road links not defined by VICS center cannot deliver traffic information despite the roads of the route guidance in the navigation system.
(2) VICS defined links provide single traffic information for one road link ID. In case of a single road where the vehicle will have different travel time depending on its orientation such as right/left turn, the VICS link provides the averaged travel time. Therefore, more high-density traffic information for each orientation at an intersection cannot be covered only by VICS link ID.
3. Function development of 2009 Model "Fastest Route Guidance"
3.1 Design Principles of2009 Model "Fastest Route search " To solve the challenges of the above, two types of high density traffic information system where the aim was to improve the traffic information of road, which was installed in the navigation system.
1) Traffic information service system to all roads of the route guidance;
Probe traffic information made from the driving information of CARWINGS users, will be delivered as traffic information for VICS not-defined links.
2) Traffic information service system according to right/ left turn
Generating traffic information of different travel time depending on its orientation at intersection from the probe information (such as right/left turn). From this, it is possible to provide plural traffic information of single intersection depending on its orientation.
3.2 Function overview of2009 Model "Fastest Route Guidance" specification
3.2.1 Traffic information service system to all roads
of the route guidance From 2008 navigation system, real-time map upgrading function was installed to download latest surrounding map from the center via mobile phone and the upgraded map from the web site with the USB memory. (Details to be published in another paper.)
This map upgrading function needs to control up-to-date maps in the center for roads newly built or lost. Additionally, it needs to upgrade the difference between comparing the upgraded map data and the navigation system's map data. Therefore, to identify the difference, the link ID that is included in the navigation system has to be identical with each road link ID that is controlled in the center. This time, using the map data, which is controlled in the center for upgrading, the system, which generates traffic information, was installed in the CARWINGS center. Until then, the system could not provide traffic information to the VICS not-defined links, but now will enable to generate and deliver traffic information by using road link ID that is controlled in the new map data. Now, it is possible to deliver traffic information even if the road link ID differs from center and navigation system.
From above, it will be able to cover 100% of the road for the possible roads of the route guidance. (Fig. 3)
Fig. 3. Traffic information cover rate of model in 2009 (100% as for the road of the route guidance)
International Scientific Journal for Alternative Energy and Ecology № 9 (89) 2010
© Scientific Technical Centre «TATA», 2010
3.2.2 Traffic information service system according
to right/left turn VICS information cannot generate traffic information of each orientation (such as turning right is x minutes, going straight is x minutes. etc) due to each road link ID is provided by the VICS center. Using the probe data collected from the vehicles, inflow and outflow road (right/left turn, going straight) was specified according to the vehicular orientation at the intersection, followed by developing the logic to measure time for each outflow road.
Fig. 4 shows a usual intersection shape where 2 roads that intersect and each orientation such as straight on /
left and right turns are available. The time from entering and going out towards each direction is defined as time for passing the intersection. Therefore, there will be 3 outflows of each direction against single inflow. This intersection can provide each direction with high-density traffic information as there are 4 inflow roads available making a total of 12 different travel times for passing. (In this example, left turn: west direction, straight on: north direction, right turn: east direction.) Furthermore, Fig. 5 shows the divergence shape such as the junction of the high way etc. There are 3 inflows and 2 outflows each, making a total of 6 different travel times for passing.
Relationship between south entering road and departing road
Departing road \
Entering road
* 4 entering roads in one intersection
Traffic information service system (When the vehicle is entering from south)
| (When the vehicle is entering from north) | (When the vehicle is entering from east) '
S^ W
30 j
XX s
S N
10 s XX s
S E
I (When the vehicle is entering from west)
XX s XX s
120 s
XX s
XX s XX s
XX s XIX s
12 traffic information from one intersection
Fig. 4. Traffic information in usual intersection shape according to right and left case
Relationship between south entering road and departing road
Departing road
i
Entering road
* 3 entering roads in the left drawing
Traffic information service system (When the vehicle is entering from south)
(When the vehicle is entering from west)
I (When the vehicle is entering from east)
S^ W
120 s
XX s
S ^ E
50 s XX s
6 traffic information from one road fork
Fig. 5. Traffic information in divergence shape according to right and left case
3.3 System configuration of2009 Model "Fastest Route Guidance"
Fig. 6 shows overall system of the 2009 model. The process flow of the traffic information is as follows.
- Center collects probe data (driving tracks information) from the navigation system using telematics.
- Identify road link ID from probe data referring the new map data.
- Generate passing time for junction and traffic information (travel time) for each road link ID.
- Generate final traffic information data by merging with other traffic information (such as VICS information etc.)
- Receive traffic information using telematics in navigation system.
- Navigation system uses the traffic information received to provide fastest route to the destination and expected arrival time.
Fig. 6. Chart of the entire system
4. Conclusion
The latest 2009 model navigation system will be able to receive traffic information of every roads of the route guidance. Additionally, new traffic information according to turning traffic when waiting for a turn etc., was installed.
Hereafter, we will continue to validate the performance of fastest route guidance function, as the quantity of
the probe data, which is based on the traffic information, will increase. At the same time review the deployment of this system globally and measurement of how to deal with the increase of probe data quantity.
Lastly, we would like to thank all the members of Clarion Company who were involved in the developing of the navigation system, Hitachi Cooperation who were involved in developing the traffic information center, and Nissan members.
International Scientific Journal for Alternative Energy and Ecology № 9 (89) 2010
© Scientific Technical Centre «TATA», 2010
