Improved Performance Track Components for Heavy Axle Loads and High Speed Rail

Abstract

North American railways have experienced significant traffic growth over the past 20 years to the point where many lines are at or near capacity. While the current worldwide recession has eased capacity constraints momentarily, the long-term trends are for continued traffic growth. Faced with the prospects of perhaps doubling freight traffic demand in the next 20 years and adding significant passenger traffic, the railroads are developing cost effective ways to increase capacity. Besides constructing additional tracks, improving the performance (i.e., safety, reliability, and service lives) of key track components is expected. Both heavy axle loads (HAL) and high speed rail (HSR) passenger traffic require high quality, durable track. The paper will describe recent work done to improve the dynamic performance and durability of these track components: • Special trackwork. • Rail joints. • Crossties. • Track transitions. For example, turnouts are being developed that can accommodate freight shippers served from mainline track that also carry high speed traffic. These continuous mainline rail switches and frogs allow slow speed diverging operations that will not affect mainline track performance. The paper will also discuss further heavy haul infrastructure research and development needs.

Investigation on Wheel‐Rail Contact and Damage Behavior in a Flange Bearing Frog with Explicit Finite Element Method

“…Greco et al and Lonetti et al [13,14] put forward a numerical strategy based on a moving mesh technique to simulate the vehicle-bridge interaction in railway bridges and then evaluated the influence of coupling effects between bridge deformations and moving loads considering the neglected nonstandard terms in the inertial forces concerning both centripetal acceleration and Coriolis acceleration, providing an advanced numerical modeling approach. Davis et al [15] put forward a finite element model for single-wheel-impact turnouts considering the accumulated plastic strain under cyclic wheel loads and the variable adaptability of profile spaces, and then a contrast analysis on the influence of three kinds of frog materials on the growth of cracks based on the obtained wheel-rail contact/shear/residual stresses and a two-dimensional (2D) crack model was performed. Pletz et al [16,17] presented a dynamic finite element model for wheels passing through frog and obtained the dynamic wheel-frog contact force and vertical wheel displacement as well as the angular velocity of the wheels, the generation of the stress field, and the plastic deformation of frogs.…”

Overview of issues and research related to special trackwork for shared high-speed-rail passenger and heavy-axle-load freight operations

“…7 Both HAL and HSR types of traffic require special trackwork components that minimize impact loads. 11 However, notable differences between HAL and HSR in terms of design requirements and loading conditions have created a variety of challenges related to special trackwork. The primary difference is the priority given to considerations for passenger comfort and diverging speed.…”

“…HSR lines require that turnouts and crossings minimize or eliminate the need to slow the train while maintaining passenger safety and comfort. 11 Increases in diverging speed and rider comfort can be achieved through optimal turnout geometries and the use of movable point frogs. 11 Another alternative is to orient turnouts such that the direction of high-speed traffic corresponds with the straight movement through the turnout.…”

“…11 Increases in diverging speed and rider comfort can be achieved through optimal turnout geometries and the use of movable point frogs. 11 Another alternative is to orient turnouts such that the direction of high-speed traffic corresponds with the straight movement through the turnout. On the other hand, special trackwork on HAL freight lines is designed to withstand the high tonnage on a specific route while minimizing maintenance.…”

“…On the other hand, special trackwork on HAL freight lines is designed to withstand the high tonnage on a specific route while minimizing maintenance. 11 Since the diverging speed is typically less important on HAL lines, the goal of innovative frog designs for HAL is to eliminate the gap in the running rails on the mainline. This may be achieved through flange bearing frogs or spring frogs.…”