Francesc Robusté

Requiem for Freeway Travel Time Estimation Methods Based on Blind Speed Interpolations Between Point Measurements

Travel time estimation from loop measurements has attracted extensive research in the last decade, resulting in numerous methodologies. Among these, those that rely on spot speed measurements at detector sites to obtain 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. This 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 carefully used and not taken as perfect. Lacking a better approach, it is recommended to avoid overcomplicated mathematical interpolations and focus 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.

Impact of High-Speed Lines in Relation to Very High Frequency Air Services

The Madrid-Barcelona air route constitutes one of the main aerial routes in the European corridor in terms of traffic demand (4.2 million passengers in 2003). To deal with such a high demand, three airline companies (Iberia, Air Europa, and Span Air) globally offer more than 60 flights per day either way. Currently, the construction of a high speed railway line between the two cities is under way. The line is expected to come into commercial service by 2007, covering the whole of the 625 km between the cities. This article analyzes the impact that high speed railway services have on air traffic demand. The results are then compared with real data corresponding to the Paris-London line, on the occasion of the launch of the commercial service of the high speed Eurostar train.

Parking management and modeling of car park patron behavior in underground facilities

Underground parking facilities in urban areas or central business districts have incorporated many information and communications technologies to provide better service, to achieve customer satisfaction, and to improve parking management. But the diversity of the off-street parking supply in terms of parking access and revenue control systems, the information offered, costs, and benefits suggests that the efficiencies of certain improvements in parking facility operations and the ultimate profitability obtained as a result of the corresponding investment made by the parking operator need to be compared. The present investigation focuses on the operations of and the behavior of parking patrons in underground parking facilities, a common type of facility in Barcelona, Spain. To model patron behavior, commonly known desegregated models based on the random utility theory were adapted to facilitate an understanding of how parking patrons decide to use a particular garage level and determine their preferences for a particular garage level. The decisions made depend on the accuracy and the convenience of the information offered. The study finds that an intelligent parking management system that tells a customer the exact locations of the available spaces is of great benefit to patrons and in the long run is a cost-effective alternative to operators because the operator can achieve financial profitability with small increases in the parking rate, and in competitive environments patrons will prefer facilities with these systems over others. The conclusions presented in this paper will be particularly useful to planners, developers, and managers.

Improvements in High-Speed Ballasted Track Design: Benefits of Bituminous Subballast Layers

Track design plays an important role in high-speed rail performance. Increases in high-speed traffic demand and maximum rail speeds will necessitate the development of new, low-maintenance structural solutions for high-speed ballasted tracks. This paper shows that use of tracks with optimum resiliency can reduce railway system operational costs. Use of an alternative to the conventional granular subballast is discussed. The results with Japanese and Italian high-speed lines showing the effectiveness of bituminous subballasts formed the basis for a study focusing on the viability of this option. With Spain used as an example, a theoretical analysis of the characteristics of the bituminous track design is presented. The results of this analysis showed that structural performance was good when a 12-cm to 14-cm conventional bituminous subballast layer was used in lieu of the usual granular layers. Also discussed are ways that a bituminous subballast can reduce track maintenance needs.

Evolution of Track Geometric Quality in High-Speed Lines: Ten Years Experience of the Madrid-Seville Line

Abstract This paper analyses the deterioration process in track geometric quality on the Madrid-Seville high-speed line, during its first ten years of commercial operation. Both the maintenance operations carried out in this period as well as all the dynamic inspection records available have been analysed. In the latter case, vertical and transversal accelerations measured on axle boxes, bogies, and vehicle bodies of Spanish high-speed trains (AVE) have been considered. The discretization of the line throughout its total extension (471 km) into 10 m long sections has made it possible to find out and quantify the relative influence of track infrastructure (tunnels, viaducts, natural subgrade, embankments, etc) on geometric track quality deterioration. The effect of switches and expansion devices in this deterioration process has also been studied.

Improving Bus Travel Times with Passive Traffic Signal Coordination

A simulation optimization model is outlined: traffic signal offsets in intersections 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 network. It also evaluates potential perturbations that may cause time variations for average performance. Moreover, 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 reduces bus travel times by an 8.5% rate in a real network while maintaining the incremental car delay below 5%.

FORMULAS FOR ESTIMATING AVERAGE DISTANCE TRAVELED IN VEHICLE ROUTING PROBLEMS IN ELLIPTIC ZONES

Some compact expressions are defined to evaluate the average distance traveled in vehicle routing problems in circular and elliptic zones. These formulas have been carried out empirically from the results obtained by the application to a set of problems of heuristic algorithms (Clarke and Wright, Fisher and Jaikumar, and Gillet and Miller) and Daganzos method based on continuous approximations of the demand spatial distribution. The problems are solved and designed automatically by a computer. Vehicle capacity has been the only constraint considered in the tour design. If N is the number of points and C is the vehicle capacity, it has been shown that the Clarke and Wright algorithm provides the best solutions especially when N < 50 or N/C < 14. However, solutions with Daganzos method are not adequate when N/C ≤ 3.

Promoting Incentives: Performance Improvement in Container Port Terminals

Most ports in developed countries have undergone the process of privatization. One of the often-cited drawbacks of this phenomenon is that, in the case of little competition among private operators, privatization simply represents 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 a private terminal operator and a stevedore company to reduce tariffs and increase the terminals 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 was successfully applied to a container terminal concession. The results suggest that an improvement both in the terminals productivity and in tariffs is possible through an annual fee that is based on an estimation of the terminals cost and tariffs in a competitive market and is paid by the private operator to the port authority.

Travel Time Measurement Using Toll Infrastructure

Travel time and its reliability are key factors in traffic management systems. They are the best indicators of the level of service in a road link and perhaps the most important variables for measuring congestion. A new approach is presented: it estimates highway travel time with the use of the existing toll highway infrastructure. A simple, efficient algorithm was developed to estimate the single-section travel time (i.e., time required to travel between two consecutive ramps on the highway) and the exit time for each ramp (i.e., time required to travel along the exit link plus the time required to pay the fee at the toll gate). With a combination of these two estimations, all required route travel times can be calculated. The proposed algorithm overcomes some limitations of other methods, such as information delay in long routes and excess travel time estimation due to accumulated exit times. The method was applied to the AP-7 highway near Barcelona, Spain, and the results obtained were reasonable and accurate.

Optimization of Handling Equipment in the Container Terminal of the Port of Barcelona, Spain

Most studies concerning port operations focus on the operation between ship and wharf. However, other port activities may also lead to congestion. In general, the capacity of the handling equipment used to transfer the container between the wharf and the storage yard is critical. This paper analyzes the internal transport subsystem in a marine container terminal and investigates the effect of the type of handling equipment used. The aim is to analyze the behavior of the handling equipment and to model its optimization. Determining a better equipment type to use is not the main concern of this paper. Queuing theory is applied, and simulation is conducted to analyze the system. To perform the analyses, measurements of parameters related to the terminal are required. These parameters were obtained from the container terminal at Barcelona, Spain, one of the best-positioned logistic platforms on the Mediterranean Sea. The results indicate that assignment of the handling equipment resources to an individual wharf crane in a particular berth is not advisable, since any decentralized decision system involves more resources. The handling equipment resources must be assigned to the berth as a whole to obtain greater efficiency, but then a focus on operation planning and reliability is required. The availability of two or three wharf cranes in a berth is not crucial in terms of efficiency; however, it could increase productivity in the berth significantly.