Abstract

Track geometry is a fundamental subject in railway construction. With the demand for increased capacity in terms of load and speed, the need for suitable transitions between consecutive track sections is highly relevant. Properly constructed transition curves lead to improved travel comfort, increased safety, and reduced wear. The well known clothoid curve is widely used as a transition curve; however, the linear curvature is not sufficiently smooth to meet the requirements for railways carrying high speed trains or heavy hauls. Blending spline curves are flexible spline constructions possessing favourable smoothness properties at the end points, which makes them considerable for use as transition curves. This paper demonstrates some selected blending splines applied as transition curves between two existing circular arc segments selected from the Ofotbanen railway. The main results in this paper are related to the smoothness at the end points and the behaviour of the curvature of the curves, where the new transition curves were shown to be smoother than the original clothoid. Another new result is the observation that the proposed method allows for the improvement of existing railways without forcing extensive changes to the original track. Some representative examples are included to highlight the flexibility of this first instance of blending splines as transition curves.

Highlights

  • Transition curves are an important development in the railway industry

  • The aim of the study was to reveal the suitability of blending splines as a transition curve, replacing one segment in an already existing railway

  • The original railway curve consists of two arc segments, of different radii, connected by a clothoid transition curve

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Summary

Introduction

Transition curves are an important development in the railway industry. The search for new types of transition curves for railways is still relevant and ongoing, due to new knowledge related to curve properties [5], where the linear curvature of the clothoid is not smooth enough in the end regions to be optimal. Both in relation to passenger comfort, for speeds above 120 km/h [6], and in relation to wear on the tracks with heavy haul traffic

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