Optimizing vehicle dynamics through a switch while maintaining existing switch lead length

Abstract

Railroad turnouts are discontinuities in the track structure that are needed to move a rail vehicle from one track to another. These discontinuities generate high dynamic forces, to include high lateral forces into and through the switch, due to abrupt or non-uniform changes in track geometry. In the diverging route, these discontinuities frequently create a need for speed restrictions. While there have been many attempts at improving turnout design, and in particular switch designs, most new designs (such as tangential geometry points) are generally incompatible with conventional (AREMA) designs and usually require additional length of track, which is often not available. Recent research has examined new switch designs, which offer reduced dynamic loading, while maintaining the existing turnout length, particularly the switch lead length, thus avoiding moving or replacing the frog, a considerable expense. One recent set of designs looks at a new switch geometry that offered significant reductions in lateral dynamic forces, as well as the potential for high speed through the switch. Successful model simulations, led to the fabrication of two prototype switches and their installation on New Jersey Transit. Subsequent field tests verified the reduction in dynamic forces and showed significant potential for reduced vehicle dynamics. On board acceleration measurements confirmed this improved dynamic behavior. This paper presents the conceptual development, modeling, simulation and testing to include comparative simulation and testing of alternate switch designs focusing on improved vehicle dynamics through the switch.