- Electric Passenger Railway which provides fast and frequent trains through a network of interconnecting underground stations via transit "lines"
- Designed to not interfere with other forms of transport above ground
- Stations sizes range from small (serving single lines) to huge (serving multiple lines and sometimes linking other forms of transport e.g. overground trains, airports etc)
- At peak times stations can become overcrowded and trains can be crush loaded
- Some older stations may not have step free access
LondonThe London Underground also known as 'the Tube' is a rapid transit system in the U.K. serving a large part of Greater London and beyond. In the year 2011/12 passenger numbers were just under 1.2 billion making it the third busiest metro system in Europe, after Moscow and Paris.
- Three bombs were detonated aboard trains on the London Underground in suicide attacks across London
- Along with a further attack on a bus in Tavistock Square, the death toll reached 52 with over 700 injuries