The metal wheels of cars and locos vibrates on the metal rail when the train travels along the tracks. The vibrations are then transferred to the underlying wooden table, or structure. The large surface of the wood amplifies the vibrations, which results in a really tiring noice. I have tested a number of different methods to reduce the noice and found the IKEA anti-slip mat to be the most effective at the lowest cost. Sandwish constructions of glued cork and rubber is of course better, but adds to the height and is too much work for me..

See thisYouTube video for more information.