01556701

Component

https://doi.org/10.3141/2476-08

This paper discusses two instrumentation techniques, linear variable differential transformers (LVDTs) and accelerometers, used to monitor and evaluate track structure behavior with the goal of nondestructively and quickly identifying track structural problems that eventually cause track geometry problems. LVDT results at a poorly performing bridge approach and corresponding open track site are used to show a relationship between poor tie support and the observed permanent vertical displacements. The existence of a gap between the bottom of the tie and the top of the ballast is expected to increase permanent ballast vertical displacements because of increased loads and vibration applied to the underlying ballast. Similarly, accelerometers show larger peak tie accelerations at ties with tie–ballast gaps and suggest that poor tie support increases applied loads to underlying ballast. Collected field data show that the tie–ballast gap can increase with time, which results in progressive loss of tie support at that tie and an increasing load on adjacent ties because of redistribution of wheel loads. The results show the need for a nondestructive monitoring system to be used with existing track geometry detection systems to improve identification of poorly supported ties. This system will guide maintenance to reduce the gap, because even a small gap can decrease tie and ballast performance and thus require remediation of a track section rather than a single tie.

01582879

15-2902

English

pp 53–58

2015

Transportation Research Record: Journal of the Transportation Research Board

9780309369213

Print

Figures (9) ; References (18) ; Tables (1)

Accelerometers; Ballast (Railroads); Dislocation (Geology); Maintenance of way; Railroad ties; Railroad tracks; Structural health monitoring; Vibration

Gaps; Linear variable differential transformers; Transition zones

Design; Maintenance and Preservation; Railroads; I61: Equipment and Maintenance Methods

TRIS, TRB, ATRI

Dec 30 2014 12:30PM

• Ballast Settlement Ramp to Mitigate Differential Settlement in a Bridge Transition Zone
• Benefits of IdaShield Signs at Highway–Rail Crossings in Idaho: Crash Analysis and Usability Assessment Survey
• Cost and Delay of Railroad Timber and Concrete Crosstie Maintenance and Replacement
• Data-Driven Wheel Wear Modeling and Reprofiling Strategy Optimization for Metro Systems
• Distracted Motor Vehicle Driving at Highway–Rail Grade Crossings
• Examination of the Effect of Concrete Crosstie Rail Seat Deterioration on Rail Seat Load Distribution
• Impact of Water Level Rise on the Behaviors of Railway Track Structure and Substructure: Full-Scale Experimental Investigation
• Influence of Frequency-Dependent Dynamic Parameters of Rail Pads on Environmental Vibration Induced by Subways in a Tunnel
• Light Rail Crossing Safety Performance Functions
• Macroscopic Models for Accident Prediction at Railroad Grade Crossings: Comparisons with U.S. Department of Transportation Accident Prediction Formula
• Railway Accidents Caused by Human Error: Historic Analysis of UK Railways, 1945 to 2012
• Sensitivity of Freight and Passenger Rail Fuel Efficiency to Infrastructure, Equipment, and Operating Factors
• Statistical Temporal Analysis of Freight Train Derailment Rates in the United States: 2000 to 2012
• Traffic Safety at Road–Rail Level Crossings Using a Driving Simulator and Traffic Simulation
• Use of Conventional Site Investigation Parameters to Calculate Critical Velocity of Trains from Rayleigh Waves
• Use of Matrix-Based Tactile Surface Sensors to Assess Fine-Scale Ballast–Tie Interface Pressure Distribution in Railroad Track