Search results for " Transportation"

Robustness in railway transportation scheduling

2008

Railway scheduling has been a significant issue in the railway industry. Over the last few years, numerous approaches and tools have been developed to compute railway scheduling. However, robust solutions are necessary to absorb short disruptions. In this paper, we present the robustness problem from the point of view of railway operators and we give some guidelines to measure robustness in timetabling. We have developed some formulae to compare robustness between two timetables based on the study of railway infrastructure topology and buffer times. Thus, each buffer time is pondered by some factors such as tightest tracks, number of subsequent trains, remaining stations, etc. This method i…

Applications of ARTIST for advanced telematics services

2007

This paper describes how telematics, also known as Information and Communications Technology (ICT), integrates telecommunications and informatics technologies to send, receive and store information via telecommunication devices. The Intelligent Transport System (ITS) is the application of telematics to the transportation area so that it allows the provision of advanced services in the mobility area in order to reinforce the efficiency, safety and effectiveness of the transportation systems. More efforts have been carried out in recent years to support the spreading of ITS and many projects have been financed in the world and, in particular, in Europe. One of the most critical problems which…

Bidirectional labeling for solving vehicle routing and truck driver scheduling problems

2020

Abstract This paper studies the vehicle routing and truck driver scheduling problem where routes and schedules must comply with hours of service regulations for truck drivers. It presents a backward labeling method for generating feasible schedules and shows how the labels generated with the backward method can be combined with labels generated by a forward labeling method. The bidirectional labeling is embedded into a branch-and-price-and-cut approach and evaluated for hours of service regulations in the United States and the European Union. Computational experiments show that the resulting bidirectional branch-and-price-and-cut approach is significantly faster than unidirectional counterp…

A negotiation protocol to improve long distance truck parking

2017

Algorithms for Pallet Building and Truck Loading in an Interdepot Transportation Problem

2016

This paper deals with the problem of a logistics company that has to serve its customers by first putting the products on pallets and then loading the pallets into trucks. Besides the standard geometric constraints of products not overlapping each other and not exceeding the dimensions of pallets and trucks, in this real problem, there are many other constraints, related to the total weight of the load, the maximum weight supported by each axle, and the distribution of the load inside the truck. Although the problem can be decomposed into two phases, pallet loading and truck loading, we have taken a combined approach, building and placing pallets at the same time. For each position in the t…

A Branch-and-Cut Algorithm for the Single Truck and Trailer Routing Problem with Satellite Depots

2016

International audience; In the single truck and trailer routing problem with satellite depots (STTRPSD), a truck with a detachable trailer based at a main depot must serve the demand of a set of customers accessible only by truck. Therefore, before serving the customers, it is necessary to detach the trailer in an appropriate parking place (called either a satellite depot or a trailer point) and transfer goods between the truck and the trailer. This problem has applications in milk collection for farms that cannot be reached using large vehicles. In this work we present an integer programming formulation of the STTRPSD. This formulation is tightened with several families of valid inequaliti…

Branch-and-Price-and-Cut for the Truck-and-Trailer Routing Problem with Time Windows

2018

In this paper, we present a new branch-and-price-and-cut algorithm to solve the truck-and-trailer routing problem with time windows (TTRPTW) and two real-world extensions. In all TTRPTW variants, the fleet consists of one or more trucks that may attach a trailer. Some customers are not accessible with a truck-and-trailer combination, but can however be serviced by one if the trailer is previously detached and parked at a suitable location. In the first extension, the planning horizon comprises two days and customers may be visited either on both days or only once, in which case twice the daily supply must be collected. The second extension incorporates load transfer times depending on the …

Mathematical models for multicontainer loading problems

2017

Abstract This paper deals with the problem of a distribution company that has to serve its customers by putting first the products on pallets and then loading the pallets onto trucks. We approach the problem by developing and solving integer linear models. We start with basic models, that include the essential features of the problem, such as respecting the dimensions of the truck, and not exceeding the total weight capacity and the maximum weigh capacity on each axle. Then, we add progressively new conditions to consider the weight and volume of pallet bases and to include other desirable features for the solutions to be useful in practice, such as the position of the center of gravity and…

Branch-and-Price-and-Cut for the Active-Passive Vehicle-Routing Problem

2018

This paper presents a branch-and-price-and-cut algorithm for the exact solution of the active-passive vehicle-routing problem (APVRP). The APVRP covers a range of logistics applications where pickup-and-delivery requests necessitate a joint operation of active vehicles (e.g., trucks) and passive vehicles (e.g., loading devices such as containers or swap bodies). The objective is to minimize a weighted sum of the total distance traveled, the total completion time of the routes, and the number of unserved requests. To this end, the problem supports a flexible coupling and decoupling of active and passive vehicles at customer locations. Accordingly, the operations of the vehicles have to be s…

Identified Risk Factors Among Truck Drivers Circulating in France

2020

The growth of the European market for road-freight transport has recently led to important changes. Moreover, due to the geographical context of France, truck drivers from different countries circulate on French roads to deliver their goods. Having road safety concerns in mind and based on a literature review, as well as interviews, a French questionnaire has been developed. Aiming at collecting data among truck drivers from different European countries, the questionnaire has been translated into seven languages and has been administered at four highway rest areas in France. The collected data were analyzed by means of multiple correspondence analysis, which pointed out new links between wo…