A cost-benefit analysis of an ad-hoc road asset data collection system using fleet-vehicles

Keeping inventories of road assets up-to-date is an important activity road authorities and mapping companies face. The information needs to be accurate as it impacts safety compliance, maintenance and ability to efficiently route cars through cities using GPS navigation devices. Such inventories are live documents and need to be updated when additions or other changes occur. Currently, authorities and mapping companies survey the roads for changes using dedicated vehicles, although due to excessive costs they are usually not able to do this more often than every few years. Recent research suggests that the overall costs of a mapping/inventory system can be significantly reduced by using an ad-hoc system of low cost automatic installations in fleet-vehicles such as taxis. This paper proposes a method to performing a cost-benefit analysis of such a system, and then applies this to the specific case of the taxi fleet of Beijing. In particular, the analysis considers the random patterns with which taxis travel over time to estimate coverage, cost as a function of number of installations and benefit as a function of surveying frequency. Since the additional benefit of a higher surveying frequency declines and the total cost of the system increases with the number of installations, the optimal number of installations can be computed that maximises the profit.