We consider the Capacitated Traveling Salesman Problem with Pickups and Deliveries (CTSPPD). This problem is characterized by a set of n pickup points and a set of n delivery points. A single product is available at the pickup points which must be brought to the delivery points. A vehicle of limited capacity is available to perform this task. The problem is to determine the tour the vehicle sho...

We address in this paper the one-commodity pickup-and-delivery traveling salesman problem, which is characterized by a set of customers, each of them supplying (pickup customer) or demanding (delivery customer) a given amount of a single product. The objective is to design a minimum cost Hamiltonian route for a capacitated vehicle in order to transport the product from the pickup to the deliver...

We address in this paper the pickup and delivery multi-depot vehicle routing problem (PDMDVRP). In this problem, a single commodity type is collected from a set of pickup customers to be delivered to a set of delivery customers by vehicles dispatched from multiple depots. The proposed problem has many applications in practice such as distribution of money between the branches of a bank, and mov...

We propose a branch-and-cut algorithm for the VRPSPD where the constraints that assure that the capacities are not exceeded in the middle of a route are applied in a lazy fashion. The algorithm was tested in 87 instances with 50-200 customers, finding improved lower bounds and several new optimal solutions.

The split pickup split delivery crude oil tanker routing and scheduling problem is a difficult combinatorial optimization problem, both theoretically and practically. However, because of the large expenses in crude oil shipping it is attractive to make use of optimization that exploits as many degrees of freedom as possible to save transportation cost. We propose a nested column generation algo...

This paper introduces an integrated approach for solving the Period Vehicle Routing Problem with Simultaneous Delivery and Pickup (PVRPSDP). The problem considers a dis tribution system consisting of a warehouse and many dispersed location retailers, where each of which having two type of demands to be delivered and collected, respectively. A fleet of capacitated vehicle is employed for deliver...

In this paper, we consider vehicle routing problems with backhauls and time windows (VRPBTW). Different backhaul variants are studied, namely clustered backhauls (CB), mixed linehauls and backhauls, and variants with simultaneous delivery and pickup and with divisible delivery and pickup. Three dimensional loading constraints are assumed. A two-phase approach following the principle packing fir...

This article studies the double traveling salesman problem with two stacks. A number of requests have to be served where each request consists in the pickup and delivery of an item. All the pickup operations have to be performed before any delivery can take place. A single vehicle is available that starts from a depot, performs all the pickup operations and returns to the depot. Then, it perfor...

This dissertation is a study on the use of swarm methods for optimization, and is divided into three main parts. In the first part, two novel swarm metaheuristic algorithms—named Survival Sub-swarms Adaptive Particle Swarm Optimization (SSS-APSO) and Survival Sub-swarms Adaptive Particle Swarm Optimization with velocity-line bouncing (SSS-APSO-vb)—are developed. These new algorithms present sel...

Though its origins can be traced back to 1977, the development and application of the metaheuristic Scatter Search (SS) has stayed dormant for 20 years. However, in the last 10 years, research interest has positioned SS as one of the recognizable methodologies within the umbrella of evolutionary search. This paper presents an application of SS to the problem of routing vehicles that are require...