Infrared thermographic investigation of railway track ballast

• Published in: NDT & E international : independent nondestructive testing and evaluation 2002-03, Vol.35 (2), p.83-94
• Main Authors: Clark, M, McCann, D.M, Forde, M.C
• Format: Article
• Language: English
• Subjects: Applied sciences; Ballast; Buildings. Public works; Emissivity; Exact sciences and technology; Heating; Infrared; Measurements. Technique of testing; Railway tracks (foundations and track subgrades); Transportation infrastructure
• ISSN: 0963-8695; 1879-1174
• DOI: 10.1016/S0963-8695(01)00032-9

A theoretical study was undertaken to determine if infrared thermography is an appropriate method to identify the condition of railway track ballast. Within this study the optimal conditions for an infrared survey were established. A laboratory experiment was undertaken to identify clean and spent ballast using an infrared camera. By cooling the ballast and watching it heat up to room temperature over time a difference in the rate of heat transfer between the two types of ballast was observed. A field trial of the infrared camera was undertaken over an operational track as part of the work within a normal track maintenance possession. The field trial identified an area of dirty ballast within a section of clean ballast and the findings were also confirmed by using ground penetrating radar and a trial pit. The laboratory and fieldwork are described in detail and sample infrared images as well as visual images of the same area are given — along with calculated values for the emissivity. The findings proved that it is possible to calibrate an infrared camera so that it can determine the condition of the ballast. Also from the success of the field trial it was shown that infrared thermography is a suitable method of identifying the condition of ballast on an operational track