Lecture11-Vehicle Routing and Scheduling.pdf - Vehicle Routing and Scheduling Introduction \u2022 The scheduling of customer service and the routing of

# Lecture11-Vehicle Routing and Scheduling.pdf - Vehicle...

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Vehicle Routing and Scheduling
Introduction The scheduling of customer service and the routing of service vehicles are at the heart of many service operations. For some services, such as school buses, public health nursing, and many installation or repair businesses, service delivery is critical to the performance of the service. For other services, such as mass transit, taxis, trucking firms, and postal service, timely delivery is the service. In either case, the routing and scheduling of service vehicles has a major impact on the quality of the service provided. 2
Input : Vehicles, service locations, depots, drivers, road network, costs, and customer requirements Aim : Find a collection of routes, each performed by a single vehicle, and starting and ending at a specified location, such that Requirements of customers are fulfilled, Operational constraints are satisfied, and a global transportation cost is minimized. 3 Routing and Scheduling Problems General Formulation
Routing and Scheduling Problems Characteristics Routing and scheduling problems are often presented as graphical networks. The Road Network represented by a directed or undirected graph represented by 𝐺 = (𝑉, 𝐴) or 𝐺 = (𝑉, 𝐸) or 𝐺 = (𝑁, 𝐴) undirected graph: all the edges are bidirectional large scale road network (countries, regions) directed graph: all the edges are directed from one vertex to another small scale road network (cities) 4
Routing and Scheduling Problems Characteristics The Road Network Customers, depot(s), road intersections are the vertices ( nodes ) of the graph represented by 𝑉 or 𝑁 𝑉 = {0, 1, … , ?} Customers : The entities requiring service Service demand: quantity of goods to be delivered or picked up time windows for service desired service start time loading and unloading times subset of vehicles that can serve them Depots Single or multiple Number and type of available vehicles Arcs can represent total time, cost or distance from one node to another. represented by 𝐴 or 𝐸 traveling cost ( ? ?? ) and traveling time ( ? ?? ) for ∀(?, ?) ∈ 𝐴 5
Routing and Scheduling Problems Characteristics Routing and scheduling problems are often presented as graphical networks. Vehicle fleets Fleet size (fixed or variable) Company or outsourced fleet (fixed vehicle cost) Vehicle capacity (maximum load allowed; weight, volume) Freight compatibility (perishable goods, dangerous materials) Compatibility with streets Costs (associated with mileage, time, fuel, journey, load) Drivers working contracts of the drivers Availability and possibility of overtime 6
Routing and Scheduling Problems Characteristics Operational Constraints: relevant to the nature of transport e.g., current load cannot exceed vehicle capacity e.g., customers in the route can require only delivery and/or collection of goods the quality of the service e.g., customers must be visited within their time windows the driving working contracts e.g., a vehicle must be used in the working periods of the drivers the other conditions e.g., precedence constraints on the customers