Margarita Novales

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.

Light Rail Systems Free of Overhead Wires

Light rail systems are experiencing a revival in several countries in the world. Nevertheless, light rail systems are facing a more demanding market and by implication the need for continuous evolution and new technologies. An example of this need is related to the requirement of avoiding visual intrusion in some areas of cities that are more sensitive to visual impacts. This sensitivity has led to the implementation of new solutions that try to avoid the need for overhead contact wires throughout the whole network or throughout the distances between stations. These solutions are generally based on the use of new systems with an embedded third rail, onboard energy storage devices, or electrical energy produced on board the vehicle. This paper explains these technologies and their applicability, as well as their advantages, risks, and inconveniences, in an attempt to clarify the available options and their reliability.

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.

Turf Track for Light Rail Systems

Light rail systems are experiencing a revival in several countries. In many new and refurbished networks, turf—or grass—tracks are being used as a means to get a reserved right-of-way that entails enhancements in the city landscape. These tracks can facilitate acceptance of the system by citizens and politicians. The visual impact of turf tracks is only one of their many advantages, which are discussed in this paper. Among the advantages are a reduction in noise and suspended fine particles, the “green lung” effect, improvements in rainwater management and heat island mitigation, and a decrease in the operational and construction costs of the system. This solution has some inconveniences, such as the need for maintenance of vegetation and for rail–environment separation, and additional precautions must be taken to ensure good performance in the long term. There are also limitations, such as the inability of buses and emergency vehicles to travel on turf tracks; additional problems in case of derailment; and possible operational incidents due to irrigation, mowing, and the combination of vegetation waste and sand. This paper focuses on explaining the advantages, inconveniences, and limitations. The intent is to provide a better understanding of the solution and to simplify the decision of whether to use turf tracks in a new light rail system.

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.

ESTRATEGIAS PARA MEJORAR LA SEGURIDAD DEL METRO LIGERO A TRAVÉS DE SU INSERCIÓN URBANA

La COST Action 1103: “Operation and safety of tramways in interaction with public space”,desarrollada entre 2011 y 2015, tenia como objetivo alcanzar un mejor entendimiento de laseguridad del metro ligero en su relacion con el espacio urbano.Durante la Accion se puso de manifiesto que los diferentes sistemas de metro ligero europeostienen filosofias totalmente distintas entre ellos. Algunas redes prestan mas atencion a laproteccion del sistema, con un planteamiento cercano al del ferrocarril convencional. Otrastratan de conseguir sistemas mejor integrados con la ciudad, facilitando la coexistencia conpeatones y ciclistas en el centro urbano, pero garantizando en cualquier caso la capacidad yvelocidad del metro ligero en el area metropolitana.En cualquier caso, a pesar de las particularidades de cada red, los metros ligeros de todo elmundo se enfrentan a retos de seguridad similares, y las soluciones aplicadas en un lugarpueden ser utiles para otras redes de nueva implantacion o existentes que se enfrenten a losmismos problemas.En esta ponencia se presentaran algunas de las medidas utilizadas por diferentes metrosligeros europeos para mejorar la seguridad de ciertos puntos diagnosticados previamentecomo puntos conflictivos (a traves de los datos de accidentes de los operadores). El origende los datos utilizados es un cuestionario sobre dichos puntos conflictivos realizado durantela Accion, que fue respondido por 24 operadores de toda Europa e Israel. DOI: http://dx.doi.org/10.4995/CIT2016.2016.3738

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.

Light Rail Transit Urban Insertion and Safety: European Experience

This paper provides a rough design tool kit to improve the safety of light rail transit (LRT) urban insertion. This tool kit was prepared after the analysis of more than 130 examples of good and bad practices related to LRT urban insertions in 13 European countries, which took place during the first working phase of the European Cooperation in Science and Technologys Action TU1103, Operation and Safety of Tramways in Interaction with Public Space. The paper deals with the design of the following aspects: pedestrian pathways at stations and stops; platform design and station and stop location; pavement treatment on shared space; pavement treatment on segregated channels; LRT separators on segregated channels; intersections (e.g., left-turn intersections, roundabouts, pedestrian and cyclist crossings, innovative solutions at intersections); LRT channel differentiation and protection by means of pavement, marks, fences, and barriers; and overhead contact system pole location.