Transportation impact assessment and trip-chaining behaviour

This paper introduces the topic of trip-chaining, then discusses further analysis to investigate trip type proportions and trip chain patterns. It is a sequel to a paper describing the author's study of trip distribution at four Sainsbury's food stores. A later paper will describe an updated methodology for forecasting the traffic impact of retail developments. In transport planning, a 'trip' is a journey between a given origin and a given destination. In transport impact studies, 'trip' is also used to describe the two trip links made before and after the stop at the development under consideration. In trip-chaining analysis, an individual is assumed to combine trips into a chain beginning and ending at home; a chain may have any number of stops and any combination of purposes. The Oxford University Transport Studies Unit was commissioned by J Sainsbury plc to conduct a household panel travel survey to assess the impact of the opening of new superstores on the outskirts of Swindon, England. This paper analyses the resulting trip type proportions, trip chains, trip lengths, and secondary trips. The findings of the study explain some of the reasons for the occurrence of variations in trip type proportions and in the origin and destination classes that have been quantified.