Articles 2010

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 hih 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.

Summary:
One of the most important challenges that confronts less-than- truckload carriers serving many-to-many distribution networks consists of determine how to consolidate flows of small shipments. The objective is to determine a route for each origin-destination pair that minimizes the cost while still guaranteeing a certain level of service. This research studies different aspects of the problem and provides a metaheuristic algorithm (based on Ant Colony Optimization techniques) capable of solving real-life problems in a reasonable computational time. The vialbility of the approach has been tested with a real case in Spain and encouragingresults have been obtained.

Summary:
Travel time for a road trip is a drivers’ most appreciated traffic information. Measuring travel times on a real time basis is also a perfect indicator of the level of service in a road link, and therefore is a useful measurement for traffic managers in order to improve traffic operations on the network. In conclusion, accurate travel time measurement is one of the key factors in traffic management systems.

This paper presents a new approach for measuring travel times on closed toll highways using the existing surveillance infrastructure. In a closed toll system, where toll plazas are located on the on/off-ramps and each vehicle is charged a particular fee depending on its origin and destination, the data used for toll collection can also be valuable for measuring mainline travel times on the highway. The proposed method allows estimating mainline travel times on single sections of highway (defined as a section between two neighboring ramps) using itineraries covering different origin–destinations. The method provides trip time estimations without investing in any kind of infrastructure or technology. This overcomes some of the limitations of other methods, like the information delay and the excess in the travel time estimation due to the accumulation of exit times (i.e. the time required to travel along the exit link plus the time required to pay the fee at the toll gate).

The results obtained in a pilot test on the AP-7 toll highway, near Barcelona in Spain, show that the developed methodology is sound.

Summary:
In one of the very first papers on traffic flow theory back in 1952, Wardrop presented the difference between the space mean speed (SMS) and the time mean speed (TMS) of a group of traveling vehicles, and derived a relationship suitable for estimating TMS, given SMS and the speed variance over SMS. As time goes by, traffic practitioners have tended towards computing TMS instead of SMS, mainly when using double loop detectors, and nowadays this is the usual practice in traffic management centers. Therefore, the useful relationship between TMS and SMS should go the other way around in relation to Wardrop’s. Recently, the complementary relationship, suitable for estimating SMS from TMS and the speed variance over TMS, has been proved. However this is not enough, as speed variance is usually not available. The present paper develops a probabilistic method to estimate SMS from TMS without the previous knowledge of speed variance and only using the usual time aggregations of double loop detector data. The main assumption of the method – the normality of vehicle speed distribution – is discussed and a formulation to obtain the expected error of the estimation is derived. The results obtained with test data from the AP-7 highway, near Barcelona in Spain, show that the developed methodology is able to estimate SMS with an average relative error as low as 0.5%.

Summary:
Road freight transportation has increased dramatically over the recent years along with its impacts such as congestion, noise and pollution. As a result, the European and USA governments have started policies to promote alternatives to road transportation, such as logistic chains containing a SSS (Short Sea Shipping) link.

Road is, by definition, a more flexible means of transportation than shipping, which is usually cheaper. Therefore, to move traffic to SSS chains it is necessary to provide fast, frequent and reliable maritime transportation. In this sense, Roll on/roll off (RoRo) vessels are the most convenient ships to be used, since they have smaller dwell times in port and, therefore, this is a kind of traffic likely to increase dramatically.

This foreseeable increase of this kind of traffic must meet with an increase of the actual capacity by means of whether improvement in performance and possible enlargements of the existing terminals or the construction of new terminals. In that sense, this paper proposes a plain methodology to calculate the capacity of a RoRo terminal, whether already in operation or during its design process, and relate it with some quality standards by means of several quality indicators which should lead to the definition of Levels of Service similar to those already used in roads and airports.

This paper ends by applying the methodology to a real terminal in Barcelona, Spain.

Summary:
Most of the ports of the developed countries have undergone a privatization process. One of the drawbacks usually pointed out against this phenomenon is that, in case of little competition among private operators, privatization represents only a change from a public monopoly to a private one. This paper focuses on concessions of container terminals with market power. The aim is to define incentive mechanisms to encourage the terminal operator and the stevedore company to reduce tariffs and to increase the terminal’s productivity at such a level as if they were in competition. For this purpose, the problem has been analyzed in the context of the Principal-Agent Theory. Particularly, a moral hazard problem with hidden information has been used. The model has been successfully applied to a container terminal concession. The results suggest that an improvement in both terminal’s productivity and tariffs is possible through an annual fee, based on an estimation of the terminal’s cost and tariffs in a competitive market, paid by the private operator to the Port Authority.

Summary:
Traditional technologies, such as inductive loop detectors, do not usually produce measurements of the quality required by real-time applications. Therefore, one wonders what could be expected from newer information and communication technologies, such as automatic vehicle location, license plate recognition, and detection of movile devices. The main objectives of this paper are to explore the quality of the data produced by Bluetooth detection of mobile devices that equip vehicles for travel time forescating and its use in estimating time-dependent origin-destination matrices. Ad hoc procedures based on Kalman filtering have been designed and implemented successfully, and the numerical results of the computational experiments are presented and discussed.

Summary:
The development of sustainable urban transport networks is a present priority for world leaders, national governors and local authorities. The challenge is to increase mobility reducing the adverse impacts of transport. The potential of Intelligent Transportation Systems (ITS) to provide solutions for the 21st century sustainable urban transport system has already been demonstrated in several piecewise applications. An integrated framework that addresses the needs of municipal authorities, that integrates the data spread through different sources, that supports the intelligent traffic & environment operations, and that provides information to the citizens steering their involvement and commitment is of critical importance and can be the enabler towards the creation of more efficient, safety, and environmental friendly transport networks that promote the citizens’ quality of life.

This work describes an integrated GPS (Global Positioning System) / PDA (Personal Digital Assistant) / GIS (Geographical Information System) system which is part of the mentioned framework. The system includes prototypes for mobile urban traffic data acquisition, with a GPS equipped vehicle, a PDA application and wireless communications, and for a geodatabase with a related Web application for urban traffic & environment. Their integrated operation is exemplified for a real urban transport system.

Summary:
This article provides new methodology for solving the bus network design problem, covering both network design and frequency setting. Two new bus network design models are created which build upon the methodology proposed by Baaj and Mahmassani (1995). One modification includes the consideration that commercial speeds of buses vary depending on the aggregated frequency of buses on each street or corridor. A further modification is the updating of route frequencies during the route generation process. The models were applied to the street network of Barcelona. Outputs were compared and it was found that the new models produce bus networks with faster average travel speeds, smaller fleet size, less route kilometer, and fewer buses per link than prior methodologies. These results demonstrate that taking the variability of bus speeds and required route frequencies into consideration when performing route generation and frequency setting can significantly improve the performance of the bus network produced.

Summary:
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.

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.

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.

Summary:
The recent worldwide crisis scenario has imposed linitations on public and private spending on new transport infrastructures. As a result, there is a need for new stricter criteria in order to prioritize some projects over others in a more socio-economically efficient way. The Project Appraisal is a common tool used for this matter.

The Value of Time (VOT) is a relevant element in transport project appraisal. On the one hand, it is essential for the calculation of the gain derived from the reduction of time for users obtained by the development of a project. On the other hand, the ex-ante prediction of demand of the planned infrastructure is made on the basis of the VOT and, consequently, its estimation is a key element for the determination of the global modal split.

This paper analyzes the VOT influence on the profitability of railway projects. Specifically, the components affected by the VOT are studied on the basis of a railway project appraisal manual. The analysis is performed from two different points of view. First, a theoretical formulation is deduced for the relation between the VOT, included in the cash flow of the different components identified, and the Internal Rate of Return (IRR), representative of the profitability of an infrastructure project. Second, a practical case for a suburban railway line is studied in order to identify the sensitivity of the IRR to the VOT, that is to say, the influence of the VOT on the profitability of the project.

Summary:
Travel time estimation from loop measurements has attracted extensive research in the last decade, resulting in numerous methodologies. Among these, the ones that rely on spot speed measurements at detector sites in order to obtain the travel time estimation on the target stretch are the most intuitive. The key issue concerning these methods is the spatial generalization of point measurements over a freeway link. The present paper shows that all speed interpolation methods that omit traffic dynamics and queue evolution do not contribute to better travel time estimations. All methods are inaccurate in congested and transition conditions, and the claimed relative benefits using various speed interpolation methods result from context specific experiments. Therefore, these methods should be used carefully, and not taken as perfect. Lacking a better approach, it is recommended to avoid overcomplicated mathematical interpolations and focus the efforts on intelligent smoothing of the noisy loop detector data, reducing the fluctuations of short time interval aggregations while maintaining the immediacy of the measurements.

Summary:
This paper presents and tests method to design high-performance transit networks. The method produces conceptual plans for geometric idealizations of a particular city that are later adapted to the real conditions. These conceptual plans are generalizations of the hybrid network concept proposed in Daganzo (2010). The best plan for a spcecific application is chosen via optimization. The objective function is composed of analytic formulae for a concept’s agency cost and user level of service. These formulae include as parameters key demand-side attributes of the city, assumed to be rectangular, and supply-side attributes of the transit technology. They also include as decision variables the system’s line and stop spacings, the degree to which it focuses passenger trips on the city center, and the service headway. These decision variables are sufficient to define and idealized geometric layout of the system and operating plan. This layout-operating plans is then used as a design target when developing the real, detailed master plan. Ultimately, the latter is simulated to obtain more accurate cost and level of service estimates.

This process has been applied to design a bus rapid transit (BRT) network for Barcelona (Spain). The idealized solution for Barcelona includes 182 km of one-way infraestructures, uses 250 vehicles and costs 42,489 €/h to bulid and run. These figures only amount to about one third of the agency resources and cost currently used to provide bus service. A detailed design that resembles this target and conforms to the peculiarities of the city is also presented and simulated. They agency cost and user level of service metrics of the simulated systems differ from those of the idealized model by less than 10%. Although the designed and simulated BRRT systems provide sub-optimal spatial coverage (Barcelona lacks BRT-suitable streets), the level of service is good. Simulations suggest that if the proposed system was implemented side-by-side with the current, it would capture most of the demand.

Summary:
This article analyses the impacts that current rail infrastructure charging systems implemented in Europe have on the competitiveness of hih speed services. It first considers the role that rail chares are supposed to play in the simulation of the growth of railway markets. It secondly focuses on the conception of the charge setting, comparing the current pratice with the one defined by the European legislation. It then presents the methodology to analyse the impacts that current rail infrastructure charges have on traffic volumes and mode split and the reults obtained.

Summary:
This article provides a methodology for solving the bus network design problem, covering network design a frecuency setting and taking into consideration that commercial speeds of buses vary depending on the aggregated frecuency of buses on each corridor. This methodology, referred to as Variable Speed MEthodology, uses a variation of an algorithm proposed by Baaj and Mahmassani that assumes speeds remain cosntant (denoted Fixed Speed Methodology). Both methodologies were applied to the street network of Barcelona. Outputs were compared, and it was found that the Variable Speed Methodology produces a Network with faster average travel speeds, shorter travel times, smaller fleet size, less route kilometer, and fewer buses per link while still serving the same level of demand. These results demonstrate that taking variability of bus speeds into consideration when performing route generation and frequency setting can significantly improve the performance of the bus network produced.