Technical Reports

FAST/HAL Rail Performance Experiment and Overview

  • 01
  • Nov
  • 1991
AUTHOR: Glenn Brave, Jon Hannafious, Roger Steele
SUBJECT: Facilities & Test Equipment, Evaluation
KEYWORDS: Rail Fatigue, Rail Wear, Rail Grinding, Rail Welding, MGT, Heavy Axle Load, High Tonnage Loop
ABSTRACT: The Rail Performance Experiment, conducted at the Facility for Accelerated Service Testing, Transportation Test Center, Pueblo, Colorado, was performed to evaluate the effect of increasing axle loads, from 33- to 39-tons, on the fatigue and wear performance of rails, ground rails, and welds. Four ancillary tests constituted this experiment: The Rail Wear Test; The Rail Fatigue Test; The Rail Grinding Test; and The Rail Welding Test. The increased axle load did cause increased rail wear rates in terms of wear in inches per million gross tons of accumulated tonnage. Under totally dry operations, the increase in wear occurred as elevated vertical wear on the high rail of the curve. Under lightly lubricated conditions, the lateral and the head height wear rates of the high rail both increased. The effect of increasing axle loads on the fatigue performance in lubricated curves was not clear. Intermediate strength rails performed noticeably worse under HAL’s in two cases, and performed better in another case. One rail type, which did not develop defects by 160 MGT under 33-ton axle loads, developed several detail fractures by 145 MGT of 39-ton axle loads. In the Rail Grinding Test, four different rail grinding practices were used in a 6-degree lubricated curve; conditioned under non-lubricated operations; ground to a worn profile; asymmetrically ground; and as-rolled. Fatigue defects developed in the ground worn, asymmetric, and as-rolled profiles. The conditioned rail did not develop defects. Electric flash butt and thermite welds were used to join test rails for the HAL test. Flash butt weld failure rates increased during HAL testing. These failures were primarily due to horizontal web cracks. A significant increase in thermite weld failures occurred in the high rails of curves during testing. Horizontal web cracks and head shelling were the two primary causes of failure.
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