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Impacto de lo cánones en la competitividad del ferrocarril de alta velocidad
Sánchez Borràs, M. and A.López-Pita
Publication: Revista Técnica de los Ferrocarriles - Railway Technology Review
Edit: RTR Spain Edition, pp 6-10
Article Language: castellano
Summary:
El presente artículo analiza como la competitividad de los servicios de alta velocidad en Europa se ve afectada por los niveles actuales de cánones por uso de infraestructura ferroviaria. Tras contextualizar la aparición del canon en la Unión Europea, se determina el nivel que debería tener este según la legislación vigente y se compara con los valores actuales. A continuación se presentan la metodología e hipótesis básicas para analizar el impacto sobre los volúmenes de tráfico y el reparto modal de una reducción del nivel actual de los cánones a los niveles deseables según la legislación europea. El artículo concluye con la presentación y el análisis de los resultados obtenidos.
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Highway travel time accurate measurement and short-term prediction using multiple data sources
Soriguera, F. and F. Robusté
Publication: Volumen “Modelling uncertaintyin traffic and transportation systems”
Edit: Transportmetrica, 1944-0987.
Article Language: english
Summary:
The development of new traffic monitoring systems and the increasing interest of road operators and researchers in obtaining reliable travel time measurements, motivated by society's demands, have led to the development of multiple travel time data sources and estimation algorithms. This situation provides a perfect context for the implementation of data fusion methodologies to obtain the maximum accuracy from the combination of the available data. This article presents a new and simple approach for the short-term prediction of highway travel times, which represent an accurate estimation of the expected travel time for a driver commencing on a particular route. The algorithm is based on the fusion of different types of data that come from different sources (inductive loop detectors and toll tickets) and from different calculation algorithms. Although the data fusion algorithm presented herein is applied to these particular sources of data, it could easily be generalised to other equivalent types of data. The objective of the proposed data fusion process is to obtain a fused value more reliable and accurate than any of the individual estimations. The methodology overcomes some of the limitations of travel time estimation algorithms based on unique data sources, as the limited spatial coverage of the algorithms based on spot measurement or the information delay of direct travel time itinerary measurements when disseminating the information to the drivers in real time. The results obtained in the application of the methodology on the AP-7 highway, near Barcelona in Spain, are found to be reasonable and accurate. In short, the travel time data fusion algorithm presented in this article tries to be as simple as possible and yet still improve the existing na ve approaches.
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A simulation study of the fleet sizing problem arising in offshore anchor handling operations
A. Shyshou, I. Gribkovskaia, and J. Barceló
Publication: Vol, 203, No. 1, pp. 230-240
Edit: EJOR (European Journal of Operations Research)
Article Language: english
Summary:
A fleet sizing problem arising in anchor handling operations related to movement of offshore mobile units is presented in this paper. Typically, the intensity of these operations is unevenly spread throughout the year. The operations are performed by dedicated vessels, which can be hired either on the long-term basis or on the spot market. Spot rates are frequently a magnitude higher than long-term rates, and vessels are hired on the spot market if there is a shortage of long-term vessels to cover the ongoing anchor handling operations. Deciding the cost-optimal fleet of vessels on the long-term hire to cover future operations is a problem facing offshore oil and gas operators. This decision has a heavy economic impact as anchor handling vessels are among the most expensive ones. The problem is of highly stochastic nature as durations of anchor handling operations vary and depend on uncertain weather conditions. Moreover, future spot rates for anchor handling vessels are extremely volatile. The objective of this paper is to describe a simulation model for the fleet sizing problem. The study was initiated by the largest Norwegian offshore oil and gas operator and has received considerable acceptance among the planners.
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Optimización de envíos en la red troncal de empresas de carga fraccionada.
Estrada, M.
Publication: Guía Logisnet 2009, pp. 12-13
Edit: Marge Books
Article Language: castellano
Summary:
Los operadores logísticos deben ofrecer un servicio flexible y eficiente para satisfacer las necesidades de distribución de bienes y mercancías de un territorio. Estas empresas presentan una red de transporte de muchos orígenes a muchos destinos cuya planificación es un problema de elevada complejidad catalogado como Np-Hard dentro de la optimización combinatoria. La principal clasificación operacional de los operadores logísticos es en relación a la consolidación de la carga. Por un lado, existen las empresas a carga completa (Full TruckLoad) donde el volumen de carga del envío de un cliente es similar a la capacidad del vehículo de transporte. En estos casos, la planificación temporal de la ruta marcada por el cliente (cargador o receptor), estableciéndose un servicio directo puerta a puerta. Este hecho hace que la gestión de rutas sea un problema altamente dinámico, con rutas variables e ineficientes debidas a los retornos en vacío.
Por otro lado, existen las empresas de carga fraccionada (Less-Than-Truckload) que ofrecen servicios de transporte para envíos de tamaño reducido. El vehículo es llenado con carga de varios clientes de forma que la programación temporal es fija y se ajusta al mayor número de clientes. Las empresas de carga fraccionada (empresas de paquetería industrial o courier) disponen de varias delegaciones que configuran una red altamente jerárquica. De este modo se identifica una red local donde vehículos de baja capacidad recogen la mercancía de los clientes de una zona y la consolidan en la delegación asociada. En ella, la mercancía es manipulada, clasificada y cargada a vehículos de gran capacidad (menor coste unitario) hacia otras delegaciones en la red troncal. En estas delegaciones en destino, el proceso se invierte y la mercancía pasa a la red local o capilar de distribución para llegar al cliente final. La red troncal presenta otras terminales de consolidación de mayor nivel jerárquico (hubs) que permiten incrementar el factor de carga de los vehículos a costa de una rotura de carga intermedia.
El diseño de envíos de la empresas de carga fraccionada en la red troncal permite la estrategia directa y la hub-and-spoke. Sin embargo, ha habido muy pocas aportaciones en las que el encaminamiento de la mercancía se realice mediante un modelo basado en rutas, de forma que se permita introducir una nueva estrategia de envío: la estrategia de paradas múltiples (stopover). Esta estrategia consiste en realizar una o varias paradas intermedias entre dos delegaciones. El objetivo de este artículo es desarrollar un modelo de diseño óptimo de rutas de la red troncal para empresas de carga fraccionada que considere estrategias de envío directo, envío hub and spoke y envío con paradas multiples.
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Performance Indicators for RoRo Terminals: Planning Assessment Tool
Morales, P. and S. Saurí
Publication: Julio 2009. Vol, 2100-2009, pp. 38-46, ISSN:0361-1981
Edit: Transportation Research Board of the National Academies
Article Language: english
Summary:
The European Union and the United States governments are showing an increasing interest in promoting Short Sea Shipping (SSS) routes as alternatives to the more pollutant and road congesting freight distribution alternatives made up of truck transportation only. These measures are likely to produce an increase in traffic at RoRo terminals, making necessary to improve their performance, enlarge them or build new terminals. Terminal managers are faced then with the problem to have to decide whereas a change in the terminal operative would suffice or it is necessary the enlargement or construction of a new terminal. It should not be forget, however, the effects that an increase in the level of usage of the terminal on the quality of the service provided, since an uncontrolled increase in use could mean reaching unaffordable levels of congestion leading to a decrease in demand. In this sense, this paper proposes a methodology to relate the level of service expected from a RoRo terminal with its capacity by the use of several quality indicators. The methodology thus proposed takes into account the ship arrivals characteristics and the service provided by the terminal and identifies which is the unused capacity of the terminal and ways to improve it and allows to estimate the effects that an increase in traffic would produce on the quality offered. The paper ends by applying the methodology to a real terminal from Barcelona, Spain.
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Impact of Two-Part Pricing Scheme on Social Welfare for Congested Metropolitan Expressway Networks.
Salas, M., F. Robusté and S. Saurí
Publication: Noviembre 2009. Vol, 2115-2009, pp. 102-109, ISSN:0361-1981
Edit: Transportation Research Board of the National Academies
Article Language: english
Summary:
Road pricing has proved to be an effective means of managing traffic demand, reducing the environmental impact of road traffic and obtaining revenues. The model employed in this paper is based on the social marginal cost economic theory to assess the total change in social welfare by means of different indicators. This model has the advantage of comparing different road pricing systems apart from the traditional ones (simple schemes), such as cordon and kilometric toll. In this case a two-part tariffs scheme has been analyzed. The results show that in order to optimize the current road capacity the two-part optimal prices must be determined (optimal combination of access toll and kilometric charge). This will allow a higher increase in social welfare. This increase is obtained by internalizing the congestion social cost (reducing deadweight loss) when diminishing demand to an optimum amount. This model has been applied on the expressway networks of the Metropolitan Area of Barcelona and conclusions show that if demand is reduced by 10%, a favorable change in social welfare takes place which is 96% higher than if demand is only reduced by 5%. Whereas if demand is reduced by 15%, such change in social welfare only increases by 20% compared with 10% demand reduction scenario.
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Rail access chares and the competitiveness of hih speed trains.
Sánchez-Borràs, M., A. López Pita, C. Nash and P. Ambrantes
Publication: Transport Policy
Edit:Elsevier
State: accepted 2009 still to be published
Article Language: english
Summary:
This paper examines rail access charges for high speed trains on new high speed lines in Europe and the impact these have on the market position of high speed rail. It examines the latest evidence on the marginal infrastructure and external costs of high speed rail, finding that the best evidence is that these are both not more than 2€/train-km. However, current legislation states that environmental costs should not be charged for unless they are charged for on competing modes. Mark ups based on Ramsey pricing principles might reasonably raise prices by 100-200%, given that infrastructure charges are only a part of the final price of rail. The paper then examines the actual prices charged in the main European countries operating high speed trains and the impact these are likely to have on traffic levels and mode split. It is found that mark ups often exceed even the optimal Ramsey levels, with a significant impact on rail volumes and market share. It is concluded that, whilst it is not surprising that governments wish to recover some of the construction costs of new high speed rail lines from users, they should consider carefully whether the level of charges is actually significantly reducing traffic on and benefits from these lines.
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Improving bus travel times with passive traffic signal coordination
Estrada M., C. Trapote, M. Roca-Riu & F. Robusté
Publication;: Transportation Research Record
Edit: Transportation Research Board, TRB, National Research Council, Washington, DC
State: Acceptat per publicació
Article Language: anglès
Summary:
This paper outlines a simulation-optimization model in which traffic signal offsets in junctions are calculated to minimize the travel time of bus users in an urban network. The model considers a passive signal priority system and restricts the maximal incremental delay caused to car users. The simulation tool is able to trace discrete trajectories of both buses and cars in a corridor. It also evaluates potential perturbations that may cause time variations respect the average performance. On the other hand, the optimization tool is based on evolutionary algorithms. The results of applying the traffic signal coordination model to a set of small trial networks are given. It is proved that the algorithm is able to design a sequence of signal offsets that improves bus travels times in an 8.5% in a real network maintaining the incremental car delay below 5%.
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Long-Haul Shipment Optimization for Less-Than-Truckload Carriers
Estrada M. & F. Robusté
Publication;: Transportation Research Record
Edit:Transportation Research Board, TRB, National Research Council, Washington, DC
State:Acceptat per publicació
Article Language: anglès
Summary:
Less-than-truckload (LTL) carriers supply freight transportation services for small parcel shipments. These companies consolidate multi-shipments in vehicles in order to guarantee the efficiency of the system. In this paper, we present a methodology to solve the long-haul routing design problem with capacitated delegations and time-constrained shipments for LTL carriers. The methodology encompasses direct, hub&spoke and stopover strategies to allocate shipments in the set of routes. The resolution method is based in a Tabu Search algorithm. The search process in the solution domain is dynamically performed with four possible perturbations. The results obtained in a set of test problems have demonstrated that the restart parameters play a significant role in the efficiency of the algorithm. On the other hand, the implementation of the computational technique in the long-haul operations network of the largest carrier in Spain has result in a reduction of 6% in transportation costs.
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