United States Department of Transportation
i
Prevention of derailments due to concrete tie rail seat deterioration
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2007-03-13
[PDF-181.89 KB]
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Alternative Title:Proceedings of the JRCICE2007 ASME/IEEE Joint Rail Conference & Internal Combustion Engine Spring Technical Conference
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Abstract:Concrete tie rail seat abrasion/deterioration (RSA) has
been an issue since the inception of concrete ties. As a
result of recent derailments involving abraded concrete
ties on curved track, the Federal Railroad Administration
set up a task force to study abrasion/deterioration
mechanisms and develop automated detection methods
using existing research vehicles. A portion of this study
reviews historical development of concrete abrasion due
to moisture or foreign materials incorporated under the
rail seat that tend to abrade concrete ties evenly across
the rail seat area. This report discusses a newly
identified concrete tie deterioration mechanism
characterized by material loss in a triangle toward the
field side of the rail seat, resulting from wheel rail
interaction involving track geometry variations.
The NUCARS™ model was used to evaluate the vertical
and lateral loading at one of the recent derailment sites
using the track geometry measured approximately one
month before the derailment. Wheel loads predicted
from the model, based on P-42 Amtrak Locomotive,
were used to evaluate the pressure distribution at the rail
concrete tie interface and were compared with allowable
design bearing pressure for concrete used in the
manufacture of concrete ties. The results indicate that
applied stress on the field side of a concrete tie due to
outward rail roll can exceed the design values. Applied
pressure distribution exceeding the design strength on
the field side tends to abrade concrete ties in a triangular
wear pattern that produces wide gage. Charts were
developed to convert measured field side
abrasion/deterioration to additional gage widening under
an applied vertical load for identifying critical locations
with wide gage defects. Further, techniques for field
inspectors to detect, measure, and evaluate rail seat
abrasion/deterioration (RSA) based on commonly used inspection technology are discussed.
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