Year of Publication

2013

Degree Name

Master of Science in Civil Engineering (MSCE)

Document Type

Master's Thesis

College

Engineering

Department

Civil Engineering

First Advisor

Dr. Jerry Rose

Second Advisor

Dr. Reginald Souleyrette

Abstract

The pressure distribution at the ballast-tie interface of railroad track plays a key role in overall track support. Failure of the ballast or tie can result from excessive loads that were not designed for, requiring increased maintenance and reducing railroad operating efficiency. Understanding the forces acting on the ballast and tie are required to design higher performance and longer lasting track. To further this understanding, the use of Matrix Based Tactile Surface Sensors (MBTSS) is employed to measure the actual pressure distribution at the ballast-tie interface, characterized by individual ballast particle contact points and non-uniform pressures. The research explores this application of MBTSS including the development of sensor protection and calibration procedures. Results from laboratory ballast box testing conducted at the Transportation Technology Center, Inc. (TTCI) are presented. Conservative estimates of peak pressure under a typical wheel load on new ballast averaged 1450 psi and on fouled ballast averaged 680 psi. Contact areas varied across the range of ballast gradations and are shown to increase under increased applied load. A parameter to describe the "roughness" of the ballast-tie pressure distribution is offered. Results from in-track testing performed at TTCI, including pressure distributions along ten test ties, are also presented.

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