Why do train tracks make a tingling or ringing noise when a train is approaching?

Question by G.: Why do train tracks make a tingling or ringing noise when a train is approaching?
Whenever a train is approaching, the tracks emit a sound I describe as “tingling”. At first I thought it had to do with electric current being passed through the third rail, but I hear this sound on non-electric tracks too. A cursory web search revealed no information about this.

My theory is that the sound is due to structural resonance from the train’s vibrations. Does anyone know for sure?

Best answer:

Answer by squeaky guinea pig
Welded tracks carry the sound of the train, the steel from which the tracks are made is a good conductor of the vibrations from the wheels, traction motors etc.

Hence the ‘singing’ sound when a train approaches.

What do you think? Answer below!

EMD/ASEA AEM-7AC 921 Approaching Mystic, Connecticut

EMD/ASEA AEM-7AC 921 Approaching Mystic, Connecticut
electric trains
Image by RyanTaylor1986
3:15am Washington DC – Boston (arrival 11:10am) on the approach to Mystic (where this service only stops at weekends). As with driving on the right in the USA, trains run on the oposite track to the UK.

The AEM-7s (dating from 1979) are to be replaced by the on order Siemens ACS-64s from 2013.

I was very disappointed with the weather on the whole trip but in hindsight it could have been worse – two weeks after flying back, Hurricane Sandy hit the US east coast.