00983181

Monograph

http://onlinepubs.trb.org...ail/hsr-42final_report.pdf

This Innovations Deserving Exploratory Analysis (IDEA) project investigated the use of ultrasonic acoustic propagation for detecting broken rail over long distances. The proposed system would use multiple wayside nodes spaced a mile apart to transmit and receive acoustic signals. The lack of a return signal implies the rail has broken. The system would use acoustic propagation in the rail as a digital communication network, allowing the system to provide broken rail protection without the installation of an additional wayside communication system. After a break has occurred the nearest nodes would use echo location to compute a range to the break. Acoustic interactions with rail were studied with frequencies from 3 kHz up to 80 kHz. Longitudinal waves in a few frequency bands were identified as having the lowest attenuation. The construction of a longitudinal wave transducer was attempted but was unsuccessful. Testing demonstrated that operation in the presence of 70 mph trains is possible except when the train is directly over the receiver. A prototype two-node system demonstrating the basic functionality of the system was constructed and operated at a range of 1.3 miles. Algorithms were developed and tested that allowed the prototype to find and track the optimal frequencies and send text data without communication other than through the rail. Algorithms for echo location were partially developed and tested. Environmental studies indicate that the optimal frequencies change 100 to 200 Hz over the day-night cycle, and rain strongly attenuates the signal.

This HSR-IDEA project was conducted by the Bay Area Rapid Transit District, Oakland, CA. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

HSR-IDEA Project 42

English

28 p.

2004-11

High-Speed Rail IDEA Program Project Final Report

Figures; Photos; References (3)

Acoustic detectors; Algorithms; Detection and identification; Prototypes; Railroad rails; Railroad tracks; Technological innovations; Ultrasonics

Innovations Deserving Exploratory Analysis (IDEA) (Program)

Broken rail

Bridges and other structures; Design; Highways; Railroads

TRIS, TRB

Dec 1 2004 12:00AM