Comparing two processing routines for GPS traces - Lessons learnt

This paper describes what may be one of the first side-by-side tests of two alternative software products for processing GPS traces into trips, and discusses some lessons learnt from the comparisons. For GPS to be useful as an alternative to self-report survey mechanisms, it is imperative that good processing software becomes available to reduce the data streams from the GPS devices into specific trips, with the various attributes of trips that are needed for modelling purposes. Currently, a number of agencies and researchers around the world have developed alternative software products, but none of these are generally open source, and comparisons between them are almost non-existent, although most make claims to certain levels of accuracy. In this paper, we describe an exercise in which two software products were used on the same GPS data set, following which a detailed comparison was made of the results. While it is interesting to see, overall, the accuracy differences between the two software products, what is of even more interest is the lessons that can be learnt about processing software in general. The paper draws some conclusions about the directions forward for processing software and processing routines in general.