A railway system that runs on one rail is a monorail.
A railway with only one rail is called a monorail.
Monorail.
A rail is a what a train runs on. A pair of parallel rails is known as a track. A train is a collection of one or more vehicles, connected together, which run on railway tracks.
The Indian Railway runs all throughout India. It is one of the world's largest railway systems with 71,000 miles of track and transporting 25 million passengers daily.
A monorail.
The Euston Railway Station is located in central London. It is the sixth busiest rail way in London. It is one of 18 railways managed by Network Rail.
monorail
a mono rail train
There are several online places where someone can book a reservation for a railway journey in the UK. Websites such as, the train line, rail easy, and national rail can all be used to book railway reservations in the UK.
Rail travel from London to Brighton became possible in September 1841. It was one of earliest railway lines in Southern England.
The best place to learn more about "One Railway" is for sure the related web site at "Direct Rail". According to that page "One Railway" was founded in 2004 and provides services between London Liverpool Street and East of England.
Thhe steeam train