Vehicle Routing and Scheduling Models, Simulation and City Logistics

Taniguchi defines City Logistics as “the process of totally optimising the logistics and transport activities by private companies in urban areas while considering the traffic environment, traffic congestion and energy consumption within the framework of a market economy”. The distribution of goods based on road services in urban areas contribute to traffic congestion, generates environmental impacts and in some cases incurs in high logistics costs. On the other hand the various stakeholders involved in the applications may have possibly conflicting objectives. Industrial firms, shippers, freight carriers, have individually established to meet consumer demands looking to maximize the company effectiveness and as a consequence from a social point of view the resulting logistics system is inefficient from the point of view of the social costs and environmental impacts. As a consequence the design and evaluation of City Logistics applications requires an integrated framework in which all components could work together. Therefore City Logistics models must be models that, further than including the main components of City Logistics applications, as vehicle routing and fleet management models, should be able of including also the dynamic aspects of the underlying road network, namely if ICT applications are taken into account. Some of the methodological proposals made so far are based on an integration of vehicle routing models and, dynamic traffic simulation models that emulate the actual traffic conditions providing at each time interval the estimates of the current travel times, queues, etc. on each link of the road network, that is, the information that will be used by the logistic model (i.e. a fleet management system identifying in real-time the positions of each vehicle in the fleet and its operational conditions type of load, available capacity, etc. – to determine the optimal dynamic routing and scheduling of the vehicle.