The phrase "underground train network" is correct and usable in written English.
For example, you could use it in the following sentence: "Rome is known for its sprawling underground train network."
Improvement of Tehran's underground train network would help alleviate the automobile-related pollution in the capital.
Meanwhile workers on London's underground train network will go on strike in sympathy with colleagues losing their jobs at ticket offices.
London has spent more than $9 billion on refurbishing its creaking transportation infrastructure — parts of its underground train network date from 1863 — in time for the Games.
Those delays, along with disruptions for hundreds of thousands of commuters traveling on London's intensively patched and refurbished Underground train network, have perpetuated concerns that the capital's transportation infrastructure remains the clearest threat to a successful Games.
Plotter Worked in London Subway LONDON, Oct. 31 (Agence France-Presse) — Critics accused London transportation authorities of a security gaffe Tuesday after learning that the son of a notorious radical imam had worked on the Underground train network.
Some members of this group were investigated by MI5 because of their links with the men who attempted to carry out a wave of bombings on London's underground train network on 21 July 2005.
The limited series, slated to run in hour-long episodes on the streaming service, will follow Whitehead's original story about Cora, a young girl born into slavery who decides to escape her Georgia plantation using the underground railroad an actual train network that will shuttle her northward.
And unlike a programme streamed over 3G or broadcast via a dedicated mobile-TV network, shows stored on an iPod can be watched on an underground train or in regions with patchy network coverage.
The "give the finger" creative proved too much for some traditional advertising channels including the London underground and some train networks, on grounds of obscenity.
As Google itself pointed out in a blog post, that's a nice little addition for when you find yourself without network in a channel, on an underground train or way out in the sticks.
Much like the London Underground, Berlin's S-Bahn is a busy metropolitan train network that survives on a strict unwritten code of conduct: commuters should avoid any form of communication with each other at all costs.
