Paper submitted to Transportation Research Board 85 th Annual Meeting, January Shinji ITSUBO Eiji HTO

Transcription

1 1 A study of the effectiveness of a household travel survey using GPS-equipped cell phones and a WEB diary through a comparative study with a paper based travel survey By Shinji ITSUBO Researcher, Traffic Engineering Division, National Institute for Land and Infrastructure Management, Ministry of Land, Infrastructure and Transport 1 Asahi Tsukuba-City Ibraki-Pref, Japan TEL: , FAX: itsubo-s8910@nilim.go.jp Eiji HATO Dr, Eng. Associate Professor Department of Civil and Environmental Engineering Ehime University 3 Bunkyo-cho Matsuyama Japan TEL: FAX: hato@eng.ehime-u.ac.jp Total words:3042(1tables and 10 FIGURES)x250=5,792words Paper submitted to Transportation Research Board 85 th Annual Meeting, January 2006

2 2 ABSTRACT In order to estimate future road traffic demand, household travel surveys have been conducted in Japan by distributing and collecting paper-based travel diaries (for example, road traffic census origin-destination surveys). There have been many reports of the problem of underreporting of trips with regard to paper-based travel diary; problems caused by the fact that respondents are dependent on their memories when recording travel activity on the travel diary at a later date and by the heavy burden of completing the travel diary. In recent years, the advance of global positioning systems (GPS) and data-handling technologies have resulted in the application of these devices to household travel surveys. Because using GPS equipment permits the clarification of the routes people have traveled, it can assist respondents to recall their travel activity, and the use of the internet can lower the recording burden, thereby mitigating the severity of the problem of underreported trips. This research established a household travel survey method combining GPS-equipped cell phones and an internet travel diary. In Japan this system is spreading for use as a method of measuring the effectiveness of the construction of new train routes and so on. This report first presents an outline of the system, then describes a study of the improvement of grasping travel activity information precision (e.g. trip rate and trip duration), and the reduction of the burden on respondents by comparing this new travel survey method with paper-based travel diaries, verifying the superiority of this newly established travel survey system.

3 3 INTRODUCTION Transportation planners and policy makers continue to be concerned with personal travel and how it changes. For this reason, household travel surveys are conducted periodically. Until now, Japan has carried out road traffic census origin-destination surveys using cars as the survey sample and a person trip survey using people as the survey sample, in order to predict future traffic volumes. These surveys have been done by having surveyors visit randomly selected respondents to ask each survey respondent to fill in a paper-based travel diary, then return to these homes to collect the travel diaries on a later date. It has often been pointed out that surveys based on these paper diaries have underreported trips and that converting the response to I/O data is time consuming and costly (1). Surveys using computers and CATI (computer assisted telephone interviews) have been studied and have been partially used, but the underreported trip problem and the inability to clarify routes remain. Recently, the increasing compactness and falling prices of GPS (global positioning systems) equipment has increased its use to conduct travel surveys (2). Because using GPS equipment permits the clarification of the routes people have traveled, it can assist respondents to recall their travel activity (3), and because the use of the internet can lower the recording burden, it is possible to overcome the problem of underreporting of trips that has been discussed in the past. Based on a comparison between a GPS based survey and past surveys done with paper or CATI, underreporting of trips has been verified (4,5,6,7). It has been proposed that travel activity be recorded by applying methods using GPS and the internet (WEB) to perform prompted recall (8). FIGURE 1 shows the improvement of survey methods ranging from paper-based travel diaries to surveys using GPS. EUnderreporting is a problem. EIt is difficult to survey routes. EConverting the response to I/O data is time consuming and costly. Year Paper-based travel survey 1960s - EUnderreporting is a problem. EIt is difficult to survey routes. Computer assisted travel survey 1980s - Computer network travel survey EOnly vehicle trip data In-vehicle GPS travel survey system Advance of Technology Travel survey system supported by a GPS-equipped cell phone and a web diary Have the above problems been solved? :Fault of suvey method FIGURE 1 Survey Methods: Technological Development and Resolution of Problems The application of GPS equipment and network equipment to travel surveys in this way has progressed. This survey adopted a travel diary that uses GPS-equipped cell phones and the WEB travel diary (below called MoALS, MoALS: Mobile Activity Logger Supported with gps-equipped cell phone). This report explains outlines of survey methods and systems related to MoALS, and then through a comparison with a paper-based travel diary, explains the effectiveness of the MoALS that was used based on a study of the improved precision of trip information (e.g. trip rate and trip duration) and the burden on respondents.

4 4 EXPLANATION OF THE GPS-EQUIPPED CELL PHONES AND WEB DIARY SURVEY Merits of a GPS equipped cell phone and WEB diary survey This research was done applying a method that combines GPS-equipped cell phones with WEB diaries. Below, the benefits of the GPS equipped cell phones and of WEB diaries are explained separately. Traffic surveys using GPS equipment include in-car type and those using PDA, but this survey used GPS equipped cell phones as survey equipment. The first reason is that in Japan, GPS equipped cell phones that can operate simple applications are in wide use and some can be obtained relatively cheaply. This application can be used to stamp the time and location of the trip start and stop point. The second reason is that in Japan, cell phone mail and applications are in wide use, and many people feel little psychological burden operating the buttons on their cell phones. The third reason is that using only GPS signals, it is impossible to perform positioning indoors or in other areas shielded from GPS signals, but a GPS equipped cell phone can estimate approximate locations based on the strength of radio waves from communication base stations. The fourth reason is that because cell phones are made assuming that they will be carried, they are resistant to vibration and shock and are compact and light weight, so carrying them imposes little burden. The fifth reason is that the third generation cell phones that will be sold in Japan after April 2007 will, in principle have a GPS function. Therefore, it is expected that GPS-equipped cell phone will be wider use than they are now. For these reasons, this survey was done using GPS-equipped cell phone. The following are the benefits of a WEB diary. Traffic surveys performed in Japan in the past have almost all been paper-based travel diary surveys. These have often placed a heavy burden on respondents because they must understand and complete diaries on A3 size paper. It is extremely easy to respond to an internet diary survey, because the respondents only click to select from destinations and the utilized traffic modes that are already displayed. The travel diary that uses GPS-equipped cell phones and the internet travel diary (MoALS) A survey respondent always carries a GPS-equipped cell phone and uses a special application to select departure at the start of each trip, then to select destination and traffic mode. On changing the traffic mode, the respondent selects transfer then selects the traffic mode and transfer location. At the end of the trip, the respondent selects arrived and enters the arrival location. The position and time calculated by GPS-equipped cell phone are automatically stamped and transmitted to a center server along with the departure/transfer/destination place and traffic mode information. FIGURE 2 shows an image of these operations and the exterior of a GPS-equipped cell phone. After returning home, the respondent edits his/her WEB diary. The first step is to access the WEB diary site through the internet and then log in. Because the items that were already entered from the GPS-equipped cell phone are displayed, the respondent checks and corrects these, then enters other information, such as purpose of the trip and the number of fellow passengers. FIGURE 3 shows an image of a web diary. During a trip, this system measures locations every 30 seconds using the cell phone s GPS function. The route can be confirmed using the WEB diary. This function helps respondents to recall travel information. FIGURE 4 shows a confirmation screen. SURVEY DESIGN Selecting the respondents The respondents were recruited using an internet mail magazine with the City of Matsuyama in Ehime Prefecture as the test region. Those without a private automobile were eliminated and a final total of 31 were selected with consideration given to balancing districts within the region. It is assumed that using a mail magazine to recruit respondents results in greater bias in the selection than random sampling, but it is assumed that because this is a pilot survey, this method of recruitment was adopted. TABLE 1 shows the attributes of the respondents.

5 5 Menu Departure Transfer Arrival Departure Point Others Home Office F Back žselect Back žselect GPS-equipped cell phone Travel Mode Walking bicycle Passenger car Bus GPS survey B L 2004/12/ sec stay Surveying your position Back Select Close Menu Repeat Every 30 sec. FIGURE 2. GPS Equipped Cell Phone Operating Screen and the Exterior of GPS-equipped Cell Phone Diary 1.Trip data 2.Transfer data 3.Comment data Menu list Place registration Route confirmation General information Log out Delete Departure time Arrival time Departure place Departure place Trip purpose Fellow passengers Park In ramp Out ramp Editing trip Editing transfer FIGURE 3. WEB Diary Operating Screen

6 6 Reduced scale button Route Close FIGURE 4. Route Confirmation Screen TABLE 1. Attribute of the respondents age Male Female Totals Totals Comparison of a paper-based travel diary and MoALS Before the MoALS survey, surveyors visited the homes of the 31 respondents to give them paper-based travel diaries used to record descriptions of trips including departure location, destination, departure time, purpose of travel and so on, and had them record information concerning trips on one weekday, December 2nd This paper travel diary was designed with reference to the road traffic census and person trip survey mentioned above. In this

7 7 step, methods of the MoALS survey and the purpose of this survey were not shown to respondents in order to prevent them from writing their papers more precisely by knowing the purpose of the survey. After the paper travel diary survey, the MoALS survey method and the use of these systems were explained to the 31 respondents. Then MoALS survey was done for five weekdays from December 6 th to 10 th, 2004, and trip information was collected from the 31 respondents. ANALISYS OF THE EFFECTIVENESS OF A MOALS SURVEY Analysis of the trip clarification precision FIGURE 5 compares the average number of trips/day from the paper-based travel diary survey and MoALS survey. Because the respondent sampling methods differ, it is impossible to perform a uniform comparison, but as reference information, the number of trips obtained by the Matsuyama City Region Person Trip Survey that was a paper based travel diary survey performed in the same region in 1970 is also shown. This FIGURE shows that while the MoALS survey trip number is 4.56, the paper-based travel diary trip number is 4.32, for a difference of about 5%. And there is a 32% difference between the MoALS and the Matsuyama City Region Person Trip Survey whose respondents were randomly selected. Similarly, trips by automobile obtained by MoALS and the paper based travel diary are compared in FIGURE 6. As reference information, the number of trips by automobiles in the road traffic census done in the same region in 1999 is shown along with them. This shows a difference of about 12% between the MoALS and the paper-based travel diary surveys. A difference of about 30% appears between MoALS and the 1999 road traffic census. All results show higher numbers of trips obtained by the MoALS than by the paper-based travel diary and the past paper-based diary surveys. It is assumed that the paper-based travel diary under-reported trips, because the answers depend on the respondents recollection, and MoALS improved the clarification of trips, because the respondents location is constantly indicated by GPS-equipped cell phones, and then respondents check the trip information using the daily WEB diary that demonstrates trip information entered with the GPS-equipped cell phone and the route calculated by the GPS-equipped cell phone. So these facts indicate that it is possible to improve the problem of underreporting trips that has been a topic of controversy for a long time % 32% 4.00 Trips itrips/person*day j MoALS Paper-based trav el diary 1970 Matsuy ama PT FIGURE 5. Comparison of Average Number of Trips/Day (All traffic modes)

8 TripsiTrips/Person*Dayj % 30% MoALS Paper-based trav el diary 1999 Road traf f ic census FIGURE 6. Comparison of Average Number of Trips/Day (only passenger cars) FIGURE 7 compares the average number of trips obtained by the MoALS and the paper-based travel diary by purpose of trip for all traffic modes. FIGURE 8 compares average number of trips obtained by the MoALS and the paper-based travel diary by purpose of trip for automobiles. In both results, the precision of the counting of numbers of trips that were regular trips to return home or to commute to and from work or school, is almost identical for both the paper travel diary survey and MoALS, but when trips for unrestricted private reasons are counted, the MoALS obtains more trips, improving the clarification of trips.

9 Trips Trips/Peron*Day MoALS Paper-based travel diary 0.00 Returning home Work Private travel Commuting Other FIGURE7. Average Number of Trips by Trip Purpose (All Traffic Modes) MoALS Paper-based travel diary Trips Trips/Peron*Day Returning home Work Private travel Commuting Other FIGURE 8. Average Number of Trips by Trip Purpose (only passenger cars)

10 10 Analysis of trip time FIGURE 9 compares duration time of each trip obtained by the MoALS and by the paper-based travel diary. The MoALS obtains continuous trip duration data by operating the GPS-equipped cell phone. The paper-based travel diary obtained responses summarizing trip duration time in convenient units of 30 minutes and 10 minutes etc. It is assumed that the paper-based travel diary obtained such results because its answers relied on memory. Trip distribution (%) Summarized in 5 and 10- minute units 0.18 Paper-based travel diary 0.16 MoALS Summarized in 1-hour 0.08 units Trip time (minutes) FIGURE 9. Trip Duration Time Distribution by the Paper-based Travel Diary Survey, and WEB+GPS Survey Analysis of the burden on survey respondents After the survey, a questionnaire survey of the respondents was conducted to study the burden of responding according to survey method. Responses concerning the ease of cooperating in the future obtained by this questionnaire survey are shown in FIGURE 10. Approximately 50% of the people supported the MoALS, while 40% of the people supported surveys using only GPS equipped cell phones or only WEB diaries, with fewer than 10% reporting that it is easier to use a paper-based travel diary. Because the respondents were recruited through a mail magazine, its results were effected by the fact that the respondents were accustomed to using the internet and that they voluntarily expressed their willingness to participate, but overall the answers were that it was easier to take part in a MoALS, and the burden of answering was lower in the case of MoALS. Although the respondents included one man and one woman in their fifties who are presumably generally unaccustomed to using computers, both people responded that they used the MoALS without any problems and their answers concerning the survey burden did not reveal any lack of understanding of or resistance to the method.

11 11 Others, non-paper-baseresponses travel diary 3.3% 6.7% Only GPS cell phone 23.3% Survey types that will be easy to participate in N=30 MoALS (GPSequipped cell phone and WEB diary) 46.7% Only WEB diariy 20.0% FIGURE 10. Cooperation with Future Surveys Limitation of the MoALS survey The MoALS survey has limitations because it uses GPS-equipped cell phones: 1) The battery life for the commercial GPS-equipped cell phones used in this survey is about three hours when acquiring locations from GPS, so the respondents had to recharge the cell phone everywhere possible; and 2) The cycle time of acquiring locations from GPS is a minimum of 30 seconds. We are now developing a MoALS system that will work for longer and acquire location with a shorter cycle time. MoALS also has methodological limitations. The MoALS survey requires a meeting to explain how to use the MoALS system, and there is the cost of cell phone communications with the center server. In view of the explanation and communications cost, this survey method is suited for continuous survey by the same person (panel survey) for one week or longer. This requires consent to participate in the survey, and so bias will arise if respondents are chosen randomly. The MoALS survey is now in the pilot study stage, and we usually recruit respondents by magazine or internet advertising. Conclusion This study compared a travel diary that uses GPS-equipped cell phones and the internet travel diary (MoALS) with a paper-based travel diary. The results have shown that the use of the MoALS survey improves the precision of the clarification of trips and may improve the problem of underreporting that has been pointed out in the past. It confirmed the improvement of the precision of its estimations of trip time. And it confirmed that the burden on respondents can be reduced and that the MoALS method is superior to the paper-based travel diary method. Because this survey method is a system that uses the WEB, it is restricted to respondents in an environment where they can access the internet at home or at work. Because it is a system that allows respondents to view the routes they traveled during their trips, it can be operated with less stress by respondents in a broadband environment. At this time, environments permitting connection with the internet do not exist in all homes, but it will soon be possible for all homes to connect to the internet.

12 12 In Japan this MoALS survey is spreading for use as a method of measuring effectiveness of the Demonstration Project of Flexible Toll Roads and the construction of new train routes and so on. These uses of MoALS are now restricted, but it is expected that it will spread gradually as a practical survey method. The Ministry of Internal Affairs and Communications has announced the policy that in Japan, the third generation cell phone that will be sold after April 2007 will, in principle have a GPS function. In the future, GPS equipped cell phones will come into wide use. Because this survey was done by loaning GPS equipped cell phones to respondents, the number of participating respondents was limited, but the future spread of GPS equipped cell phones is expected to eliminate these problems. In the future, the spread of the internet and development of GPS equipment will expand the application of these devices to traffic movement surveys.

13 13 REFERENCES 1. Hato, Eiji. and Asakura, Yasuo. New approach for collection activity diary using mobile communication systems. TRB Annual Meeting, CD-ROM, Transportation Research Board, National Research Council, Washington, D.C., Wagner, D. P. Battelle, Report: Lexington Area Travel Data Collection Test; GPS for Personal Travel Surveys, Final Report for OHIM, OTA, and FHWA, Prashanth K. Bachu, Trisha Dudala, and Sirisha M. Kothuri, PROMPTED RECALL IN GLOBAL POSITIONING SYSTEM SURVEY: PROOF-OF-CONCEPT STUDY, In Transportation Research Record: Journal of the Transportation Research Board, TRB, National Research Council, Washington, D.C., Timothy L. Forrest, David F. Pearson, Ph.D., A Comparison of Trip Determination Methods in GPS- Enhanced Household Travel Surveys, CD-ROM, Transportation Research Board, National Research Council, Washington, D.C., David F. Pearson, Household Survey Trip Under Reporting A Case Study in Laredo, Texas, CD-ROM, Transportation Research Board, National Research Council, Washington, D.C., Jean Wolf, Michael Loechl, Miriam Thompson, TRIP RATE ANALYSIS IN GPS-ENHANCED PERSONAL TRAVEL SURVEYS, CD-ROM, International Conference on Transport Survey Quality and Innovation, Johanna Zmud, Jean Wolf, Identifying the Correlates of Trip Misreporting - Results from the California Statewide Household Travel Survey GPS Study, CD-ROM,10th International conference on Travel Behavior Research, Peter Stopher, Andrew Collins, CONDUCTING A GPS PROMPTED RECALL SURVEY OVER THE INTERNET, TRB Annual Meeting, CD-ROM, Transportation Research Board, National Research Council, Washington, D.C., 2004