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.