Mind the gap!! In most lines of the following text, there is one unnecessary word. It is either grammatically incorrect or does no fit in with the sense of the text.

The London underground

1. The London underground has been much in the news recently, first when
2. access to the line to the Millennium Dome
   it
   it
   was restricted at the opening
3. ceremony to the prime Minister and his entourage, and afterwards when it
4. became a bone of contention between candidates in an election that took
   the
   the
5. place for the post of Mayor. Despite travellers' complaints, the fact remains
6. that with road traffic in the city hardly able to move, there is no better way of
7. getting
   out
   out
   from one place to another. The first line was opened in 1863 but the
8. system soon grew
   up
   up
   to be the second largest in the world, after the New York
9. Metro. The trains ran along tunnels constructed by digging a deep trench,
10. filling the sides with
    a
    a
    brick and then covering it over. perhaps the most
11. exciting innovation on the underground, though,
    there
    there
    was the first escalator,
12. installed at Earls Court in 1911. The moving staircase was an American
13. invention and had been operating for a
    long
    long
    number of years in stores and at
14. exhibitions but the authorities were rather doubtful whether most
    of
    of
    people
15. would make
    their
    their
    use of it. In order to reassure travellers, they employed a
16. man with a wooden leg to ride up and down on it all
    one
    one
    day long to show
17. them how safe it was. They need not have worried. It soon proved so
    much
    much
18. popular that people went down it just for the pleasure of coming up again!