Assessment of Dynamic Properties and Scope of Implementing a New Track Transition Curve

Abstract

This paper discusses the possibility of replacing the commonly used clothoid transition curve on a railroad route with a new transition curve adapted to railway operational requirements. The new transition curve is similar to the clothoid in its initial section, but it differs significantly over its extent, especially in the final section, where it provides a smooth entry from the transition curve into the circular curve. The subject of this study is the consideration of two key aspects of transition curves: the dynamic properties of the proposed geometric solution and the conditions related to the replacement of the existing clothoid transition curve. The dynamic analysis carried out confirmed that from an operational point of view the new transition curve is more favorable in the initial section than in the clothoid, while in the final section it has a definite advantage. In the final section the superiority of the new transition curve over the Bloss curve (representing S-shaped transition curves) is demonstrated. In our analysis of technical conditions related to the replacement of the clothoid with a new transition curve, it was shown that this operation does not require large lateral shifts of the railway track, and the values of the shifts depend mainly on the extent of the transition curves and the angle of shift of the main directions of the route. In the most unfavorable cases (large turn angle, considerable extent of transition curve) the situation can be significantly improved by a relatively small reduction in the radius of the circular curve.