The Educational Railroading Conference Leader Since 1994


Ali Tajaddini

Ali Tajaddini
Program Manager in Office of Research & Development


New High-Speed Adjustable Perturbation Slab Track

Validation of track geometry measurement and vehicle-track interaction testing are critical functions for safety and operations of railways, especially for high speed passenger train operations. In 2014-2015, under FRA’s sponsorship, a testing facility was designed and built at the TTC, located near Pueblo, Colorado in the United States of America, which allows a test track with precisely adjustable track geometry and track property (stiffness and damping) variations. This testing facility is a part of the already existing high speed test track referred to as the Railroad Test Track, a 13.5 mile (21.7 km) loop that has speed capabilities of up to 180 mph (290 km/h) in tangent sections and a limiting speed of 162 mph (261 km/h) in a 1o15’ (1,400 m in radius) reverse curve.

This test facility (Figure 1) includes the concrete slab track with the specially designed tie plates that are adjustable so that a maximum vertical perturbation of 1.75 inches (44.5 mm) can be installed while lateral adjustment of 1.5 inches (38.1 mm) is possible on either rail. Specially designed plates and shims allow track geometry deviations with a resolution of 1/8 inch (3.2 mm). Details of the plates and fastening design that allow precise track geometry perturbation adjustment are also shown in Figure 1 (photo on the right). In addition, by using rail seat pad or vertical shim with different rubber pads, various track stiffness and damping properties can be achieved.

This test track section can be used to accurately create different types of track geometry anomalies at different wavelengths, including surface, gage, alignment, and cross level deviations, and combinations of these types. It is designed to test the adequacy of track geometry measuring vehicle accuracy as well as for validating vehicle-track interaction model simulations. Validation of vehicle-track interaction models can be used to certify equipment for high speed rail operations.