I believe that light commuter trains should have rubberized wheels. Much of the noise is steel-on-steel action.
If you've ever had a rubber bushing wear out in a car's suspension linkage, you know what I'm talking about: thunk, clang, squeak!
If you've ever had a rubber bushing wear out in a car's suspension linkage, you know what I'm talking about: thunk, clang, squeak!
It goes from a loud clanking to the hum of the tube.