The method would need to be self contained and could not involve setting up significant apparatus or equipment. Anything used would need to conform to railway regulations. The coils are mainly blocked with dust and fibre from a railway application.
I responded before I realised that you were from TfL although I guessed that it would be a mtro project. i did a lot of work on colling in the London Underground environment a few yers ago as part of Project connect. You might want to call offline since this is likely to be a bit specialised! 07968 721 958 or [email protected]