Global Positioning System (GPS) devices are emerging as a potential means to collect improved data on the spatial aspects of personal travel. This paper builds on earlier work by Stopher and others on the use of passive GPS devices, for which additional non-GPS data may be added through a subsequent prompted recall survey. This paper presents sets of rules which can be applied to the raw data acquired by wearable GPS devices to determine the modes of travel used and the trip ends. Experiments have been performed in which the devices were tested for a range of different situations, including collecting data on trains, buses, and ferries, collecting data in urban canyons and also with respect to the cold start phenomenon. The paper also describes the procedures undertaken to download and analyse the data
