The Time-Dependent Pollution-Routing Problem (TDPRP) consists of routing a fleet of vehicles in order to serve a set of customers and determining the speeds on each leg of the routes. The cost function includes emissions and driver costs, taking into account traffic congestion which, at peak...

This paper presents a continuous approximation model to determine the long-term vehicle fleet composition needed to perform distribution activities. The problem is a realistic variant of the vehicle routing problem, in which the fleet size and mix are also decision variables. The types of...

This paper introduces the fleet size and mix pollution-routing problem which extends the pollution-routing problem by considering a heterogeneous vehicle fleet. The main objective is to minimize the sum of vehicle fixed costs and routing cost, where the latter can be defined with respect to the...

Consolidating small freight shipments into vehicle loads allows more efficient and frequent shipping by concentrating large volumes onto relatively few transportation links. This paper analyzes three schemes for routing freight shipments via consolidation terminals in an idealized many-to-many...

Time definite freight transportation carriers provide very reliable scheduled services between origin and destination terminals. They seek to reduce transportation costs through consolidation of shipments at hubs, but are restricted by the high levels of service to provide less circuitous...

Hub and spoke designs have been adopted by many air carriers and motor carriers in recent years. This paper compares rectilinear distance transportation costs for hub networks with two types of demand to investigate how well an idealized model predicts the cost for real-world demand. The...

We present an overview of continuous approximation models that have been developed for freight distribution problems. A taxonomy of six classes is used to differentiate the problems and a brief review of each paper is provided. This paper stresses important principles and key results from the...

Urban regions contain a hierarchy of roadways, ranging from a dense network of low speed local roadways to sparser networks of higher speed roadways. Because minimizing travel time is usually more important than minimizing travel distance, vehicles may detour from the route of shortest distance...

This paper develops a continuous approximation model of a general freight carrier serving a fixed region with an increasing density of demand. Terminal, transportation and relocation costs are considered. As the demand for service by a freight carrier increases, transportation terminals are...

In this paper we study the problem of locating a new station on an existing rail corridor and a new junction on an existing road network, and connecting them with a new road segment under a budget constraint. We consider three objective functions and the corresponding optimization problems,...