Technical Reports

FAST/HAL Ballast and Subgrade Experiments

  • 01
  • Aug
  • 1991
AUTHOR: M. Carmen Trevizo
OFFICE: RPD
REPORT NUMBER: FRA ORD-91/10
SUBJECT: Evaluation
KEYWORDS: Subgrade, Heavy Axle Load, Facility for Accelerated Service Testing
ABSTRACT: The ballast and subgrade experiments were conducted during the first 160 MGT of Heavy Axle Load (HAL) traffic to determine if the increase in axle load, 33-ton to 39-ton, generated a measurable difference in the performance of the four selected ballasts and the typical subgrade found at the Facility for Accelerated Service Testing (FAST), Transportation Test Center, Pueblo, Colorado. Dolomite, limestone, granite, and traprock were tested to determine their capability of supporting traffic in a 39-ton axle load traffic environment. Track geometry retention and ballast degradation were monitored during the test. All four ballasts were able to withstand the HAL environment, but the dolomite and limestone required an out-of-face surfacing before the end of the first phase of the HAL program. The Subgrade Experiment was conducted to determine if an increase in axle load produces a significant increase in subgrade stresses. Data from the test reflected the increase in axle load at the ballast/subgrade interface. The increase varied with the track support condition.
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