Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
origin, destination, and route data are automatically col- lected by the GPS, relieving the participant of recording this information. Second, all trips are automatically recorded, reducing potential issues with unreported trips. Third, trip start and trip duration entries are auto- matically recorded. Fourth, the GPS data can be used to verify the reported trips and activities. Finally, this approach allows data to be downloaded from the PDAs in a format that can be directly used for analysis, reduc- ing postprocessing data reduction costs. Possible issues associated with this approach relate to potential errors and reliability concerns with GPS, the storage capacity of PDAs, the battery life of PDAs, and the costs of PDAs. None of these issues should be major concerns. ⢠The conceptual design of the system includes two geographical user interfaces (GUIs), a GPS logger, a data structure, a data quality control module, a trip identifier module, a geographic information system (GIS) module, and a communication module. The modular structure allows for customization to specific applications. The GUI contains the household and activity- based surveys. Participants enter demographic and activity- travel infor- mation in the household survey GUI at the start of the survey period. This information is stored in the activity diary and household data module. The GPS logger receives and stores location and time data. If an individ- ual forgets to record a trip or activity, the trip is auto- matically recorded in the GPS data log. During the survey period, participants enter activity information into the GUI. The activities and trips are monitored by the GPS. The data integrity checks module detects incon- sistencies between the information entered by the partic- ipant and the GPS data log. Data on the PDA is downloaded through the communication module. The data can be processed and analyzed through the use of GIS and other analysis tools. The system can also be pro- grammed to query the participant about changes in planned activities and trips. ⢠The GPS- enabled PDA system is being deployed as part of a large- scale activity- travel survey in Flanders, Belgium. The results from this survey will be used in other activity- based modeling and research activities. The results will also be used to fine- tune the GPS- enabled PDA system and make any needed modifications. Johanna Zmud, NuStats Partners, LP, moderated this session. 37SURVEY METHODS
