Analysis of child diaries - Can GPS traces of parents movements provide sufficient travel data for children?

Global Positioning System (GPS) devices are moving into the mainstream for undertaking household travel surveys. However, in all applications to date, it has been decided to give GPS devices only to household members above a certain age (generally in the range of 12 to 14 years). Although some experiments have been done where GPS devices are provided to younger children, this has been in the context of special studies and not a broad household travel survey. In a recent effort in the USA, a GPS-only household travel survey was conducted on households in the Greater Cincinnati area. GPS devices were provided to all household members in sampled households over the age of 12 years. Child diaries were, however, provided for each child in a sampled household 12 years old or younger and a parent was asked to complete summary travel information for each such child for a 24-hour period. In this paper, an analysis is reported of these child diaries, to determine to what extent a child's travel can be inferred from the parents' travel and from a knowledge of the school attended by the child, and what travel information is lost by not providing a GPS device to each young child. This has important implications for the potential for GPS to replace conventional diaries in household travel surveys.