The phrase "a third railway" is correct and usable in written English.
It can be used when referring to an additional railway system or line that is being introduced alongside existing ones.
Example: "The city plans to invest in a third railway to improve public transportation options for its residents."
Alternatives: "an additional railway" or "a new railway line".
A second railway station is under construction in the north of the city.
The government of Ma-laysia's new prime minister, Abdullah Ahmad Badawi, left, has shelved indefinitely plans to build a second railway the length of peninsular Malaysia, at a cost of 14.5 billion ringgit ($3.8 billion).
A transport expert has said it would be "very difficult" to get a second railway line into the south-west of England approved, despite the main link at Dawlish being destroyed by storms.
In 1903, a second railway station was opened in Giffnock, Whitecraigs railway station.
Crystal Palace used to have a second railway station, the Crystal Palace High Levell) railway station.
On 8 January 1996 Eurostar launched services from a second railway station in the UK when Ashford International was opened.
Radstock had a second railway station on the Somerset & Dorset Joint Railway extension to Bath, which closed to passengers in 1966.
In 1984, the government decided to build a second railway tunnel and a second road tunnel to alleviate traffic congestion in the Cross Harbour Tunnel resulting in Eastern Harbour Crossing, the first railway-road tunnel in Hong Kong.
A second railway, the East Somerset, opened a branch line from Witham in 1862 and built a station to the east of Priory Road.
Could anything be more ludicrous than to waste the time of the Committee in discussing such things presented by such a body!" A second railway company, the Edgware & Hampstead Railway (E&HR), also had a bill before Parliament which proposed tunnels beneath the Heath as part of its planned route between Edgware and Hampstead.
