Locations of rapid track condition deterioration are typically well known to railway track engineers, although the cause and methods of improvement may be unclear. The rapid deterioration of these locations can be due to many factors such as poor conditions of the components (rail, tie, and ballast) or failure of any of the components or subgrade. The exact cause of the problem is generally unknown as attempts to maintain the track in acceptable condition (by surfacing or undercutting) are implemented. In conjunction with track geometry measurements, which help to identify poorly performing track locations, track load-deflection behavior can contribute to the knowledge of the cause of the problem, with an ultimate goal being identification of a cost-effective, long-term solution to improving the performance of the track. Fundamentals of track load-deflection behavior, how track behavior relates to performance, indices that can be used to determine suitable maintenance strategies, and the relation of these indices to actual track performance all contribute to the evaluation. As indications of the track load-deflection behavior, several track stiffness measurement techniques that have been proposed and tested are described. The goal is to clarify the need to measure track stiffness and to identify rational means of relating the data to track condition and, ultimately, to ensure maintenance, renewal, and safety.

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Two types of commercially available dynamic earth pressure cells were tested to determine their suitability for measuring traffic-induced stresses in subgrade. The main consideration was how well the gauges could be calibrated for accurate representation of soil stresses. Tests were conducted with fluid pressure applied directly to the cells and with cells buried at various depths in a soil test chamber. The effects of soil type, proximity of adjacent cells, major principal stress direction, and temperature were investigated. Results indicate linearity, hysteresis, sensitivity, conformance, and accuracy. The two cells performed differently, but one was much more accurate than the other.

Providing a safe, reliable, and maintainable railway infrastructure is a formidable challenge in Amtrak's complex operating environment. Presented is the design description of the Infrastructure Information Management database, including the latest developments and incorporating vehicle-track interaction measurements. Also shown is how wayside measurements combined with a record of train movement to define the traffic and utilization of the railway infrastructure. An example of the use of the system is discussed to illustrate how the combined information will assist the maintenance managers in determining when and where to invest resources to optimally maintain the railway infrastructure. Also addressed is how wayside and record of train movement can be used to allocate maintenance costs to the various service providers.