A monotrain is a rail based transportation system based on a single rail, that acts as its sole support and its guideway.
Warren Grafton takes Jeff Tracy, Brains and Tin-Tin on-board a Pacific-Atlantic Monotrain for a test ride of his fully automated mono train. However, a storm caused a helijet to crash into a portion of track, and the lack of crew meant that the four had to stop the train themselves before it crashed off the track. It appeared in Brink of Disaster.
The Anderbad Express Monotrain in The Perils of Penelope.
- Main article: Anderbad Express
The Zombite Monotrain from The Uninvited.
- Main article: Zombite Monotrain
Tracy Island Monotrain
- Main article: Inspection Monorail (Tracy Island)
Thames River Monotrain
The Thames River Monotrain from Thunderbirds.
In the Thunderbirds Are Go! episode Hyperspeed, Professor Tycho Reeves tests his new Hypercar, which is essentially a single-car monotrain travelling through a vaccuumless tunnel. Unfortunately, a minor fault in Reeves' calculations results in the hypercar being unable to stop, forcing the Tracys to attempt a complex rescue with Thunderbirds 1, 2 and 4 to transfer the passengers and destroy the tunnel. Reeves subsequently makes plans to recreate his project with help from Brains.
One of the outstanding features of Mr. Steelman's secret underwater lair was the monorail scooter seen inside its access tunnel.