This is a trigger to be placed where the train crosses over a bridge to simulate the sound of a train crossing a bridge. It makes a clickety-clack noise, (like a train over points), when trains pass over it. It may not work in all versions of Trainz. Set Trigger Radius to '1'. (Modifided by Dave Snow with permission from Boat (thanks!). )
See instructions in dialogue box or a full tutorial at www.boatztrainz.co.uk