Orientation in London: - One-Two-Go London: The Ultimate Guide to London 2014 - page 130

All lines are identified by name (Circle Line, Central Line, and Piccadilly Line). Many
lines have multiple branches rather than running point-to-point so always to check the
train's destination (which is shown on the front of the train, the platform indicator screens
and will be broadcast on the train's PA). Some branch lines (such as the Chesham branch
of the Metropolitan Line or the Kensington Olympia branch of the District Line) run as
shuttles and require a transfer onto the 'main line'. Note that the Northern Line has two
separate routes through the city center which split at Euston and rejoin at Kensington, one
(officially called the Charing Cross Branch but known by locals as the West End branch)
runs through the West End serving Leicester Square, Charing Cross and Waterloo, while
the other route runs via the City of London (officially called the Bank branch but also re-
ferred to as the City branch) with major stops at Kings Cross and Bank.
Despite the confusing layout of the line, it is fairly easy to work out which way your train is
going; for example a northbound Northern Line train to Edgware along the Charing Cross
branch will be displayed on the indicator as 'Edgware via ChX' and the on-board PA will
announce 'This train terminates at Edgware via Charing Cross'. Finally, note that direction
signs for the platforms indicate the geographical direction of the line, not the last stop of
the line. It is always advisable to carry a pocket Tube map (available free at most stations)
to help you with this.
Almost all stations have automatic ticket barriers. If you pay by Oyster Card, just tap your
card against the yellow pad to open the barriers (both upon entrance and exit). If you have
a paper ticket, insert it face-up into the slot on the front of the machine, and remove it from
the top to enter the station. If you have a single-ticket it will be retained at the exit gate. If
you have luggage or if your ticket is rejected there is normally a staffed gate as well. Paper
tickets can be purchased from vending machines in the station lobby. There are two types
of machine: the older machines that have buttons for different fare levels and accept only
coins and the new touchscreen machines that have instructions in multiple languages, offer
a greater choice of ticket and accept bills and credit/debit cards (note that if your card has
no embedded microchip, you cannot use these machines, you pay at the ticket counter).