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C. Holm, M. Anzek, S. Kastela: Travel Time Information Service Utilising Mobile Phone Tracking CAJ HOLM, B. Se. Technology and Management Traficon Ltd Review Uinsiportti 4, FIN-02210 Espoo, Finland U. D. C.: 656.025.2:654.165 E-mail: [email protected] Accepted: Apr. 3, 2003 MARIO ANZEK, D. Se. Approved: Jun. 15,2004 E-mail: [email protected] SLOBODAN KASTELA, D. Se. Fakultet prornetnih znanosti Vukeliceva 4, 10000 Zagreb, Republika Hrvatska TRAVEL TIME INFORMATION SERVICE UTILISING MOBILE PHONE TRACKING ABSTRACT the real-time traffic monitoring system required for these services on the whole main road network. Finnra This paper discusses the suitability of mobile phone posi­ has estimated that the costs of implementing a con­ tioning data for travel time information. The Finnish National ventional traffic monitoring system on the main road Road Administration Finnra has carried out a study on the network are about 42 million Euro and the annual subject (1) and managed pilot installations on two road sec­ maintenance costs are about 10 per cent of the invest­ tions (6) in order to determine the feasibility of mobile phone ment. tracking for traffic monitoring and management purposes. Ac­ cording to the study and the pilots, the mobile phone position­ The basic idea discussed in this paper is tracking of ing can provide useful link monitoring data, i. e. the travel time cellular telephone equipped vehicles as traffic probes. and speed. Mobile phone tracking was found to be a very prom­ The task of Finnra's mobile phone tracking study (1) ising tool for implementing travel time information service to was to identify such positioning methods of existing drivers. telephones, that could provide accurate data for traf­ fic management services, be easily expanded to the en­ KEYWORDS tire main road network, and that would not compro­ mise privacy and would be economically feasible. mobile phone tracking, information service, travel time, travel So far, Finnra alone has been responsible for traf­ speed, traffic monitoring and management fic monitoring. The new techniques, such as mobile telephone tracking, involve more players in providing data. Innovative methods are introduced providing 1. ABOUT TRAFFIC MONITORING hopefully also lower costs of service and freedom of METHODS choice to the users. Private operators, on the other hand, get a new market area for their services. The focus area of the nearest future traffic man­ Various positioning methods including both satel­ agement activities in Finland is provision of the basic lite based and several cellular telephone based meth­ traffic management services and implementation of ods were studied. Their accuracy, coverage, suitability Time Typical Typical Cove- Suitabili- Depend a Initial Usage Standar- table accuracy accuracy rage ty for bility cost cost disation (rural), m (city), m mass- from location operator Cell ID available 2000- 200-1000 excellent excellent small small small yes 8000 Signal available 500-3000 100-500 moderate moderate small small small no level Correlation 2-3 250-1500 50-200 moderate moderate small moderate moderate no (DCM) years? Time 2-3 200-1000 100-200 moderate low high high high yes difference years? GPS 10-30 30-100 good low none none none yes A-GPS 2-3 10-30 30-100 good+ low high high moderate yes years? Figure 1 - Comparison of various positioning technologies Promet- Traffic- Traffico, Vol. 16, 2004, No. 4, 211-216 211 C. Holm, M. Aniek, S. Kastela: Travel Time Information Service Utilising Mobile Phone Tracking Availability Sate lite-based remote technologies -----------------, ' Network-based ' ' technologies ' ' ' rural ' ' RTKGPS ! GPS ' (AGPS) Cell I. D. ' ' + RTD suburban ' ' WLAN-based ' -----------------·' urban/city indoor underground f-- ---,----,----t-----,--- --,,----'--.--..._-'-r-----,,-----,--'---,--.J---,-- 0.1 0.3 3 10 30 100 300 1K 3K 10K 30K Accuracy/[ m] Figure 2 - Comparison of various positioning technologies for mass positioning, operator dependability, initial Some potential obstacles for link monitoring were and operational costs and standardisation level were also identified. Actually, the movements of tele­ assessed. The near future development, the possibili­ phones, not vehicles are monitored. Various types of ties offered by new techniques and privacy and legal vehicles have typically different numbers of active mo­ aspects were also studied. The focus of this paper, bile hand-sets onboard: a car may have only one hand­ however, is not to discuss the technologies but rather -set while a bus may have dozens on board. In some to give only an overview of the comparison of the tech­ cases the main roads that should be monitored and nologies which are presented in Figures 1 and 2 (2 and secondary roads, or even a main road and a railway 3). run parallel for tens of kilometres. Mobile telephone tracking could in such cases monitor the whole trans­ port corridor instead of the desired road. It was as­ 2. THE USE OF MOBILE PHONE sumed that in networks, the telephones could quite TRACKING FOR TRAFFIC easily be switching back and forth between two or even MANAGEMENT more cells. Mobile phone tracking was not expected to be use­ The second phase of the study defined the require­ ful for point measuring. It could provide information ments for the monitoring data in various operational about the passing phone and the passing time. How­ environments and for various traffic management ser­ ever, there is no method for such a vehicle classifica­ vices. The available methods enable observation of tion, speed measuring, etc. It would also not give traf­ the passage of a telephone, observation of the passage fic volumes at a measuring point but the volume of time and putting an identifier (session-ID) on it in or­ passing telephones. Mobile telephone tracking was in der to observe when the same device passes another brief estimated not to be useful for point measuring. point that is of interest for the monitoring task. A pas­ Another assumption was that incident detection mak­ sage means that the device enters an observation area, ing use of mobile telephone tracking would be a diffi­ the size of which varies from several tens of square cult task. It would most probably require development kilometres (cell-ID method in rural areas) to a few of new types of parameters, for instance a sudden ac­ hundred square metres (GPS). cumulation of mobile phones, and their interpretation According to the study, the mobile phone position­ algorithms. Also, other questions should be solved, ing can provide useful link monitoring data for infor­ such as detecting on which carriageway on a dual car­ mation about the travel time and speed. The required riageway road the incident is. basic data, passage of a vehicle (actually a mobile tele­ The main conclusion of the study is that the data phone) and the passage time can be reliably recorded. gathered by mobile telephone tracking is most suit­ This data can be utilised both for individual links and able for information about traffic fluency, traffic flows for wider road or street networks taking into consider­ on a link and travel time, and information about road ation the accuracy requirements of various operatio­ maintenance works. The travel time and average nal environments. speed between two points can be calculated. The mo- 212 Promet- Traffic- Traffico, Vol. 16, 2004, No. 4, 211-216 C. Holm, M. Anzek, S. Kastela: Travel Time Information Service Utilising Mobile Phone Tracking vement of road maintenance vehicles and other spe­ were generally very close to those achieved by license cial vehicles can be monitored and corresponding in­ plate recognition. No needs for modifications of the formation given to drivers. GSM-network were identified. Finnra started to­ gether with VTT a thorough evaluation that was com­ pleted last November (6). 3. PILOT INSTALLATIONS AND THEIR The pilots made use as probes of all the mobile INITIAL RESULTS phones that were switched on in the area. Using anon­ ymous session-ills protected privacy of the owner. Finnra has set up two pilot installations of provid­ The positioning was done when a telephone switched ing monitoring data for travel time information service from one cell to another but only certain points were making use of mobile phone tracking. It was assumed monitored, three points on the Ring Road I and four that there were quite many open factors regarding the points on Highway 4. The data was collected in one­ positioning technologies and their applications. The -minute intervals. Figures 3 and 4 show results of both telecommunication operators could have had various the mobile phone tracking and license plate recogni­ new solutions available for such a service but for confi­ tion systems on the same links on Highway 4 (Figure dentiality reasons they did not provide the informa­ 3) and Ring I (Figure 4). tion. Finnra proceeded through tenders and detailed The pilot study showed the advantages and the dis­ negotiations with the operators to implement the two advantages of the system. A significant advantage is pilots. The invitation to tender defined the quality re­ the capability to produce travel time observations re­ quirements for travel time data but no exact method to gardless of the predominant traffic situation or the en­ produce these. Another basic requirement was that vironmental circumstances. Figure 5 shows the differ­ the pilot was not to violate the road users' privacy. ence in observations between licence plate recogni­ The chosen pilot sites gave the possibility for com­ tion and mobile phone tracking in bad weather. parison between the two existing license plate recogni­ Because of the large amount of observations, the tion pilot systems installed on the same road sections traffic situation could be interpreted easily and the in 1999. In tests, both license plate recognition systems statistical variances and parameters based on travel were found to be effective and give correct travel time times calculated and estimated reliably.

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