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190 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 2 geographic information system, it is necessary to survey are in wide use in Japan. It is possible to record the travel the contents of trips through ancillary questionnaire sur- path and departure and arrival times by using the phones veys and other means. as well as to correct input data and implement various The probe person survey system is one that, on the ancillary surveys through a web diary in combination basis of the advantages and problems to be solved for with them. Hato et al. (2006) implemented a successive such existing studies, aims to achieve the goals of (a) day-to-day survey for several months on the same indi- ensuring accurate travel records through spacetime viduals as a three-wave panel survey (Figure 2). position determination functions of high accuracy, (b) The survey was composed of agent-type application reducing recording omissions through timely travel software for GPS mobile phones, a web diary system, behavior recording functions, and (c) ensuring improved and a position data management server. Test subjects efficiency of data coding by the investigator and improv- were asked to carry mobile GPS phones and to press the ing the sense of participation in surveys of subjects start or stop button at the time of departure or arrival, through a system that emphasizes real-timeness and respectively, through the agent-type application soft- interactiveness. ware. Doing so determined origindestination data and A survey system of high timeliness is constructed that departure and arrival times for the trip. Position data allows travel records to be input anywhere through the were recorded every 20 s while the subject was traveling, use of both mobile phones and the web as input media. and position data of about 5 to 10-m accuracy was This process allows subjects to record travel in a timely transferred to the data management server if outdoors. manner while they have a clear memory and to check By a series of such processes, path data were automati- and correct the travel records. Moreover, in a long-term cally determined. The results of trips were instantly survey in which mobile phones with position determina- reflected in a blog-type web diary system that could be tion functions are used to establish spacetime position, viewed, with corrections being possible for any omis- it is necessary to obtain data of high accuracy while sions related to the purpose of the trip and means of reducing the burden on subjects. To this end, it is impor- transportation. Furthermore, correcting the web diary tant to have a GUI that allows subjects to check visually was also possible from mobile phones by using their and to edit both the data they recorded through the Internet function. information input and the travel records obtained Long-term recording became possible in a diary-like through mobile communication systems, which comple- sense for test subjects because they could verify what was ment each other. An example of such a survey is a suc- recorded about their trips via a map on the Internet. cessive diary survey of about 3 months. Through input via mobile phones, the agent application A survey has been proposed in which the contents of software transmitted transportation data. A mechanism individuals' behaviors are identified by using accelerom- to prevent omissions was made possible by using the eters, barometers, and sound sensors rather than imple- transmitted traffic data as an incentive. Furthermore, menting questionnaire surveys as a complement to a this survey system proved to be stable with existing behavior survey that uses mobile phones and a GPS. In mobile phone systems and capable of supporting large- such a survey, transport mode is identified by the magni- scale studies. tude of acceleration; the floor of a subject is identified by atmospheric pressure; and the behavior content is identi- fied by variability in acceleration and sound. It is aimed at automatically recognizing the behavior content by preparing sensor signal sequence data corresponding to behavior patterns, such as transport mode and activity content, as training data. Survey methods using multiple sensors can be said to allow a long-term behavior survey of high quality to be achieved by reducing the burden of input on subjects in the survey. APPLICATIONS OF SURVEY TECHNIQUES Wide Area: Probe Person Survey The most versatile survey technique of those described in the previous section is the probe person survey, in which subjects are asked to carry GPS mobile phones, which FIGURE 2 Outline of probe person systems.