Technical Reports

Studies for Rail Vehicle Track Structures

  • 30
  • Apr
  • 1970
AUTHOR: H.C. Meacham, R.H. Prause, D.R. Ahlbeck, J.A. Kasuba
SUBJECT: Track, Track/Train Interactions
KEYWORDS: Track Structures, Concrete Beams and Slabs, Vehicle Dynamics, Track Interactions, Track Costs, Vehicle-Track Interactions
ABSTRACT: Conventional (tie-type) and non-conventional rail vehicle track structures were studied, with the restriction that standard gage and rail-head contour be used. Computer programs were developed and used to analyze track response to both static and dynamic vehicle loading. The models of conventional track were validated by track, and on the Penn-Central high-speed track near Bowie, Maryland. The DOT research cars were used to obtain a series of controlled-speed passes at speeds up to 125 mph. Track response under Metroliner and regular freight traffic was also recorded, both at a joint and away from a joint. The measurements showed the lack of consistency of track characteristics at different locations and at different times, and indicated the computer results to be as accurate as the degree to which track parameters could be defined. The predicted presence of individual pressure pulses for individual axles on trucks with wheelbases exceeding 6 1 was verified by measured subgrade pressures 3 1 beneath the tie base, at speeds up to 125 mph. A major philosophy in the developmentĀ· of improved track structures was to reduce the magnitude and number of pressure cycles transmitted into the roadbed, with the number of cycles reduced by using beam and slab type rail supports having substantial longitudinal bending stiffness. Following the analysis, performance specifications were written for rail fasteners and three types of reinforced concrete structures recommended for further evaluation in field tests: cast-in-place slab, cast-in-place twin beams, and precast twin beams.