Living directly in view of a metro entrance within the inner city will be have noise from people using it, but one minute walk away is considered perfect in Europe.

Many people who visit me for the first time comment on this.

On the very quietest summer night, when there's no ventilation systems running etc, I can sometimes hear an occasional dum-dum, dum-dum when I lie in bed. The tunnel is directly under the building.

In suburbia closer is also better, but away from the track is better than along the track of it's above ground.

The idea of security concerns sounds ridiculous to me.