United States Department of Transportation
i
Engineering studies in support of the development of high-speed track geometry specifications
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1997-03-01
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[PDF-104.65 KB]
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Abstract:The Federal Railroad Administration has been directing engineering studies to support the development of high speed track geometry standards. These standards are intended to cover train operating speeds from 110 mph to 200 mph. The studies conducted include evaluation of the use of measuring track geometry with offsets from several chord lengths, computer simulations of vehicle response to track surface and alignment variations, application of the proposed specifications to previously measured track geometry, and comparison of
proposed specifications to foreign practice. The proposed standards use multiple chords to control surface and alignment geometry. Single isolated geometry variations are allowed greater amplitudes than three or more repeated geometry variations. The results of the engineering studies indicate that use of multiple chords is effective in controlling a wide range of geometry variation wavelengths, from less than 30 feet to greater than 250 feet. The computer simulation
studies show that at high speed, wheel/rail interaction dominates
vehicle response to short wavelength (less than ~100 feet) alignment variations, while carbody motions dominate vehicle response to long wavelength variations. Derailment and carbody accelerations are the principal concerns in vehicle response to track geometry variations. Application of the proposed specifications to previous measurements of high speed track on the Northeast Corridor indicates a relatively modest number of exception locations (~1 location every 3 miles).
Comparison of the proposed specification with foreign practice indicates that the proposed specification provides a generally similar level of control of track geometry.
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