Visualising trips and travel characteristics from GPS data

Road & Transport Research, Jun 2003 by Stopher, Peter R, Bullock, Philip, Jiang, Qingjian

CONCLUSIONS

The visual displays shown in this paper, which have been produced using the rule-based algorithms discussed herein, provide effective communication of the extensive data available from the GPS devices. However, it is clear that a comprehensive set of rules are required to permit automated reduction of the huge amounts of data available to parsimonious displays of the data.

From an analysis of known trips recorded by GPS and the application of the rules discussed in this paper, we have determined that there is about a five per cent error rate in both detecting false trip ends, and in failing to detect real trip ends. This five per cent is only partially correctable by manual procedures. Some false trip ends are likely to remain in the final data presented to respondents, and some trip ends will not be detected. However, the prompted recall survey provides a mechanism to correct most of this error.

The programming that has been accomplished has done more than provide ways in which these data can be represented. It has also reduced significantly the time and effort required to handle the data. A fully manual procedure was found to take between one and two person days to translate the data from one day of GPS data collection from a vehicle to the maps and tables shown in this paper. However, with the software we have developed, this has been reduced to about an hour of work. This makes it possible to process large amounts of data from GPS devices, and permits full-scale application of GPS measurement in fieldwork exercises that would probably be impractical without the software.

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