Look, here comes the library van! Optimising the timetable of the mobile library service on the Isle of Wight

Abstract

This article describes an approach taken to optimise the timetable of the mobile library service operating on the Isle of Wight. The mobile library visits over 90 communities on the island, offering books, DVDs, videos and CDs, and operates on a periodic timetable. The optimisation problem is formulated as a multiple travelling salesmen model with additional time-balancing constraints on route durations. The article also shows ways in which data required for the model, in particular travel times, were gathered, and discusses practical issues arising in pre-processing the data to fit the purposes of the case study. The model is used to produce an improved timetable over the current one that implies driving time reductions of up to 25 per cent and yields routes that are better balanced in terms of time spent on the visits made each day. The model is also used to test various scenarios differing with respect to the number of locations visited and days over which the service operates.