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TURNOUTS
New Concepts for Turnouts in Urban Rail Transit Infrastructures

The word ‘turnout’ describes the junction in trackwork where lines diverge or converge. Although a turnout consists of several components, this project focuses on the most expensive component: the frog. The frog is the section of the turnout that enables the wheel that is running on one rail to literally cross over another rail. The project considers the following types of frogs: cast manganese, welded, moveable nose, flange bearing and deep groove. The TURNOUTS project focuses on the design and manufacture of new turnout concepts for rail infrastructure. Project partners include the main European turnout manufacturers as well as research and engineering organisations, one contractor and three end users.

Background

There is a significant difference between railway operations and urban transport (tram, metro) operations. The main one is speed. The speed varies from 100 km/h for a freight train to 160 km/h for medium-distance trains to 350 km/h for high-speed trains. In comparison, the maximum speeds of a tram and metro are far lower at respectively 50 and 100 km/h. Railway axle loads range from 18 tonnes for passenger coaches to 22.5 tonnes for freight and locomotives, whereas axle loads for tram and metro range from 8 to 14 tonnes. Railways usually face fewer geographical and thus environmental concerns, as they run separately, typically at a greater distance from residences. Metros and trams face significant space constraints as they operate in an urban environment. Metro tracks are in a tunnel and turnouts cause great concerns, especially in terms of noise and vibration. Trams operating on the streets, often close to residences, cause similar problems. In addition, trams operating on the street require special (girder) rails and thus special turnouts. All these elements show that, even though the basic concepts are the same, turnouts developed for railways cannot be simply implemented in urban transport.

Objectives

The objective of this project is to improve the vehicle-track interaction of turnout systems as used in urban rail transit, and therefore improve their efficiency, enhance their safety levels, reduce their maintenance costs, increase their life expectancy and restrain the emitted noise.

Description of work

The TURNOUTS project starts with the modelling of actual turnouts to provide the benchmarks against which the improvements will be measured. Design changes will be implemented in the models to predict their behaviour. The turnouts will then be manufactured and installed for validation purposes and measurements will be performed to confirm the predictions from the models. The end result will be a series of turnouts with improved characteristics. The project is divided into several work packages (WP):

WP1: Six different existing turnout systems representing the conventional turnouts used today will be measured and modelled. The models will be optimised to reflect the actual measurement results. Improvements and changes will be made to these turnouts. The models are than used to optimise the proposed changes.

WP2: A large number of potential measures to reduce impact forces will be defined. Conceptual design studies will be made for some of these designs.

WP3: Seven test sites will be selected within the networks of the participating operators and the most optimal design for each particular location will be developed.

WP4: The most optimal designs will include the use of new materials, new manufacturing techniques and new installation techniques. The selected designs will be manufactured and tested in the lab.

WP5: After installation, the performance of the designs will be tested and compared against the calculated results.

WP6: The results of the new designs will be used to develop conclusions about the benefits of various designs.

Results

The project focuses on design and manufacture of new construction concepts of special trackwork for rail infrastructure that are low maintenance, high quality, safer, risk mitigating and produce lower noise. Complete turnouts will be considered in the research project (frog and switch area) with the exclusion of the control systems. At the start of the project, two different modelling procedures for impact force calculation during vehicle running in turnouts will be compared for their performance and validated. A first comparison will be made comparing measurement and modelling results on a reference turnout. Further refinement will be made by updating modelling results by means of measurement results on six different turnout systems, which are representative for the conventional turnouts used today in urban rail transport networks (WP1). Also at the start of the project, a large number of potential design measures for reducing impact forces will be defined. A conceptual design study of these design measures will be made (WP2). In the second phase of the project, seven test sites will be selected (three end users) and for each test site the most optimal new turnout design will be developed (iterative procedure in terms of refining selected turnout or in terms of selection a new turnout design) (WP3). The newly developed turnout systems will be manufactured (WP4), tested in the lab and installed on site. This will include the use of new materials, new manufacturing techniques and new installation techniques. Their performance will be measured and compared against the calculated results (WP5). At the end of the project, conclusions will be drawn in WP6. The consortium includes the main European turnout manufacturers, research and engineering partners, a contractor and three end users.

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