Interface - The Journal of Wheel/Rail Interaction

OPTIMIZATION

Optimizing Wheel and Rail Profiles on Amtrak's Northeast Corridor
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The contact distribution was evaluated through a computer model that superimposes a set of measured wheel profiles on a given pair of rail profiles and performs a quasi-static curving balance. Information on the vehicle's weight, axle load, speed and truck characteristics, along with track parameters such as gauge, curvature and super-elevation, are used to model the wheel/rail interaction. The information generated by the Pummeling Analysis provides a practical method for identifying the position and severity of the wheel/rail contacts and determining the longitudinal creepage, rolling radius difference and contact stress associated with each.

Sharable, Expandable Database
CSTT worked with Amtrak's comprehensive Sharable, Expandable Database (SED) to understand track conditions on the corridor (see sidebar Monitoring Vehicle/Track Interaction on Amtrak's NEC.) Track geometry data in the SED, which is updated about every two weeks, includes data on the track gauge, curvature and superelevation for any point on the track between Boston and Washington. Measured rail profiles, collected at 4 1/2-foot intervals across most of the NEC by Advanced Rail Management under subcontract to the FRA, were also employed in the analysis. A speed and braking torque profile for an Acela train was provided by ENSCO, Inc. and imported into the SED database.

A comparison of the wear performance of the unworn Amtrak-Standard wheel, which measured profiles at three stages of wear, and the new CSTT-designed wheel profile was performed using CSTT’s pummelling software. Thirty-six thousand curving simulations were run for each profile to determine the distribution of the frictional work (which is generally accepted as a good proxy for wear) experienced as the train runs the full length of the NEC mainline from Washington to Boston. This evaluation determined that the frictional work at the flange root of the new wheel profile design is about half of what it is on the Amtrak-Standard wheel-profile design.

While the unworn Amtrak-Standard wheel makes very little contact with the gauge corner of worn rail, because of its strong two-point contact it encounters frequent gauge-face contact with the outside rails in curves on the corridor. The new CSTT design makes fewer gauge-face contacts over the same length of track.

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