Exactly 3 seconds

There used to be a coal mine at the bottom of the blue moutains which is now a tourist attraction.

One of the big things they have is a kind of train that takes you down to the bottom, but it's so steep it's almost vertical.

Originally the track was just a series of carts which would haul coal to the top, but eventually people started hitching a ride on them to avoid the equally steep walk back to the top.

It's hard to explain just how steep this is, but we were both hanging on for dear life as the tiny, uncovered train trundled down the mountainside.

Apparently when the train first opened to the public one of the first women to take the trip asked the drive what would happen if the brakes failed..."in exactly 3 seconds this train would come to a complete halt" he told her.

What he actually meant was that teh incline was so steep that it would only take 3 seconds for the train to come off the track, hurtle groundwards and immense speed and use the bottom of the ravine as it's brakes.