Alfonso Orro

Use of a genetic algorithm to optimize wheel profile geometry

Abstract Wear is a very important subject for railway administrations. Therefore, it would be of interest to develop a methodology for designing wheel profile geometry in order to improve its behaviour in relation to this subject. Until now, existing approaches of this kind are based on the statistical study of wear wheel profiles, but this do not consider the characteristics of vehicles and railway tracks, and in addition, it is not an option when a vehicle is going to run, for example, over two different types of track over which mixed running has not previously happened. In the current paper, a new general methodology is presented for improving wheel profiles in relation to certain physical phenomena that arise during the running of the vehicle over the tracks. This methodology is based on the genetic algorithm (GA) technique. To show the power of this procedure, it is applied to an application case (of a tram-train in Spain), in which great improvements in the behaviour of wheel profile are achieved. In the light of this application, the importance of definition of indexes which control the evolution of the GA is shown.

The tram-train: State of the art

Abstract In response to the demand for improved mobility in metropolitan areas, the 1990s saw the development in Europe of a new transport system known as the tram-train. This system is based on the use of conventional railway lines with a low traffic density in order to extend urban tram or light rail services without the need to change vehicle, incorporating them into railway traffic. This allows for a wider range and scope of direct transport services and reduces waiting times and changes. The operation of light rail vehicles on conventional railway infrastructure involves finding solutions to a number of technical issues such as traction power supply system, rolling stock design, gauge, tyre and rail profile, structural strength, passenger access, signalling, etc. This paper describes these problems and the solutions arrived at by services currently in operation, or in advanced planning stages, worldwide.

Tram-Train: New Public Transport System

In response to the demand for improved mobility in metropolitan areas, the 1990s saw the development of a new transport system in Europe known as the tram-train. This system is based on using conventional railway lines with a low traffic density to extend urban tram (streetcar) or light rail services without changing vehicles, incorporating them into railway traffic. The tram-train enables a wider range and scope of direct transport services and reduces waiting and transfer time. The operation of light rail vehicles on conventional railway infrastructure requires the solution of numerous technical issues, such as traction power supply system, rolling stock design, gage compatibility, tire and rail profile, structural strength, passenger access, and signaling. Such problems are described and their solution by services now operating, or in advanced planning stages, worldwide is discussed.

Geometry of High-Speed Turnouts

Turnouts are singular points of the railway track. In the past 20 years, a series of advances has added to their design as well as to the design of other elements of the track structure. These developments have allowed vehicles both to increase their running speed over the turnouts and to improve their reliability and security, and thus reduce maintenance costs. This paper focuses on geometric improvements in turnouts that permit high speeds over direct (350 km/h) and diverging (160 to 220 km/h) tracks. These improvements are related to diverging track alignments. The improvements include transition curves, switch rail design, and mechanization that have been adopted to avoid the straight switch rail strike phenomenon, and they include crossing modifications that avoid the existence of the gap.

Madrid tram-train feasibility study conclusions:

Abstract The tram-train concept consists of the operation of a light rail system that can run either on existing or new tramway tracks, or on existing railway tracks, so that the services of urban public transport can be extended towards the region over these existing railway tracks, with much lower costs than if a completely new line were built. The authors have developed a research project about the feasibility of such a system in Madrid (Spain), extending newly created light rail networks through local Renfe (National Railways) lines, or through the Metrosur line (a circular metro line of new construction in the south of the city). The aim of the paper is to explain the conclusions of this research project in relation to the main technical issues that must be solved to develop this system.

Buses with High Level of Service in Nantes, France: Characteristics and Results of the BusWay Compared with Light Rail Transit

This study identified and analyzed the reasons that have led the BusWay of Nantes, France, to be one of the most, if not the most outstanding and successful case of setting up a bus with high level of service (BHLS) system in European cities. The lessons and the conclusions from the study may be applicable to and useful for other sites with similar conditions. The analysis examined the measures that were implemented (infrastructure, vehicles, design of transit service operations, complementary facilities and services, and branding) and the results (level of service in frequencies and operating speed, reliability of schedules, ridership, and traffic safety). Furthermore, as BHLS and light rail transit (LRT) are integrated in the same level of the trunk network in Nantes, the city provided a relatively level playing field to develop an equitable comparison of the two systems. Through the case study of Nantes, the study found that the BHLS system was suitable for meeting demand volumes in the range from 1,000 to 2,500 passengers per hour in one of both directions during peak hours with a level and quality of service very near the LRT, but with more moderate investment costs and higher flexibility.

Box‐Cox Mixed Logit Model for Travel Behavior Analysis

To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their principal areas of application. In the transport field, they have mainly been applied to mode choice, but also to the selection of destination, route, and other important decisions such as the vehicle ownership. In usual practice, the most frequently employed discrete choice models implement a fixed coefficient utility function that is linear in the parameters. The principal aim of this paper is to present the viability of specifying utility functions with random coefficients that are nonlinear in the parameters, in applications of discrete choice models to transport. Nonlinear specifications in the parameters were present in discrete choi...

The tram-train: Spanish application

The tram-train concept was developed in Karlsruhe, Germany, in 1992 by connecting several railway network lines to the tramway network of the city. This paper provides a brief summary of the tram-train systems operations today, and it then explains the main advantages of the system as it could be applicable in Spain. Specifically, discussed is a research project about establishing such a system in Madrid.