The use of thermal imaging in mechanical diagnosis is, and always has been, a go to technology to determine matters such as bearing failure before it actually happens as it will show abnormal heat signatures. The term mechanical ranges from heavy industry and the condition of engines, status of aeroplane components including the body integrity, to Formula 1 cars. The application of thermal imaging is massive and, in reality, there is an incomprehensible range of applications for where it is being used and on what. However, as always, it is the interpretation of those images that is the key and that is where a thermal imaging qualified practitioner is essential.
You may not be aware that the channel tunnel trains have thermal cameras fitted front and rear to monitor the infrastructure as they pass through. While we are looking at transport users these range from the Police to Railtrack, TFL and many many more in-between.