CONGRÉS |
 |
|
 |
88th Transportation Research Board Annual Meeting - TRB
Lloc i data: Washington, del 11 al 15 de gener de 2009
Presentació:
Congreso de carácter anual del Transportation Research Board (TRB), una de les institucions del National Research Council americano dedicada a la investigación en temas de Transporte.
Ponències:
- "Rail Infrastructure Charging Systems for High-Speed Lines in Europe". Sánchez-Borràs, M i A. López-Pita.
- "Long-Haul Shipment Optimization for Less-Than-Truckload Carriers". Estrada, M. i F. Robusté.
- "Improving Bus Travel Times with Passive Traffic Signal Coordination". Estrada, M., C. Trapote, M. Roca-Riu i F. Robusté.
- "Impact of Two-Part Pricing Scheme on Social Welfare for Congested Metropolitan Expressway Networks". Salas, M., F. Robusté i S.Saurí.
- "Long- Run Marginal Cost in the RoRo Industry". Saurí, S. i B. Spuch.
- "Performance Indicators for RoRo Terminals: Planning Assessment Tool". Morales, P. iy S. Saurí.
|
|
PONÈNCIES |
|
|
 |
Rail Infrastructure Charging Systems for High-Speed Lines in Europe.
Autors:Sánchez-Borràs, M i A. López-Pita.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
In the European railway framework, the expenses of rail infrastructure cost are partly covered by the Governments and partly by the infrastructure manaers through the infrastructure charges that operators pay to them for running services on the infrastructure they manage. However, thet extent to which infrastructure charges cover infrastructure costs is higher for high speed lines (HSL) than for convetional lines. This communication characterizes the infrastructure charging systems for HSL implemented in Europe and analyses the level of charges applied to these lines with the aim of quantifying if mark.ups above marginal cost are being charged to high speed services running on the European HSL. The reults obtained show that, despite the reat differences between charging systems for HSL, important mark-ups above marinal costs are applied by all the systems analyzed and that common features between them can be established.
|
|
 |
Long-Haul Shipment Optimization for Less-Than-Truckload Carriers.
Autors:Estrada, M. i F. Robusté.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
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.
|
|
 |
Improving Bus Travel Times with Passive Traffic Signal Coordination.
Autors:Estrada, M., C. Trapote, M. Roca-Riu i F. Robusté.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
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%.
|
|
 |
Impact of Two-Part Pricing Scheme on Social Welfare for Congested Metropolitan Expressway Networks.
Autors:Salas, M., F. Robusté i S.Saurí.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
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.
|
|
 |
"Long- Run Marginal Cost in the RoRo Industry"
Autors:Saurí, S. i B. Spuch.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
In this article a quantitative analysis of the cost structure a shipping company has to take into account when starting and running a regular Ro-Ro cargo line is carried out (a Shot Sea Shipping line, for instance). The aim of the paper is to find an expression for the totoal costs depending on the parameters of the analyzed route, bearing in mind that the vessel capacity will be an important factor. This model will apply to rolled cargo vessels, especially truks or plataforms. Once the costs function is obtained the long run marginal costs will also be obtained, depending on the line capacity, aiming to obtain the optimum pricing, according to microeconomic theory. Frequency and regularity reflected upon the amount of scales will also be considered to be important because the long run marginal costs will depend on the amount of acales and the amount of transportated platforms/trucks.
|
|
 |
"Performance Indicators for RoRo Terminals: Planning Assessment Tool"
Autors:Morales, P. i S. Saurí.
Congrés: 88th Transportation Research Board Annual Meeting - TRB
Lloc i Data: Washington, del 11 al 15 de gener de 2009
Idioma: inglès
Resum:
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.
|
|
|
