Airborne "Tie Sonar" for High-speed Tie Deflection Measurements
Tie-ballast interface deterioration from July 2013 CSX train derailment
"Tie-sonar" concept for in-motion tie deflection measurements
Chirped pulse compression for super-resolution range finding
Funding:
Department of Transportation/Federal Railroad Administration
Burlington Northern Santa Fe (BNSF) Railway (in-kind)
Purpose:
To develop a system able to track the vertical deflection of railroad ties autonomously at revenue speeds (e.g. 60 mph) or higher.
Synopsis:
The Vertical Relative Rail Seat Displacement (VRRSD) is a metric indicative of bending failure of concrete and wood ties. The July 2013 derailment of the CSX freight train in NY was caused by deteriorated conditions at the tie-ballast interface. Tracking the vertical deflection of the ties can indicate deterioration of the concrete tie-ballast interface, which can result from various factors including tie bottom abrasion, ballast pulverization, and voids in the tie-ballast interface. UCSD is developing a system that can track the deflection of the ties in a completely non-contact manner during normal train operations. The idea is to use an array of air-coupled ultrasonic transducers operated in a pulse-echo mode and using special signal processing routines for real-time and accurate tie position measurements.