Places where there is no radio signal.
Trains receive their authority to proceed through a section from the
dispatcher(s). These days they receive this authority by radio. The
dispatcher gives a complete description of the authority detailing what
section the train has authority to proceed into including mile post
numbers, etc. The train engineer (=driver for us Brits) then repeats the
whole item back to the dispatcher and it is only when this has been done
(correctly) that the train has authority to proceed.
If a moving train's authority has to be amended, or if the dispatcher
wants to contact the train in case of emergency they will do this by
radio. If there is no radio signal (mountains, etc) then the train is in
'dark territory' and cannot by contacted by normal means.
A Taxi driver licensed for London and Brighton
In the UK they have RETB (Radio Electronic Token Block) for long
single track sections like the Camrian main line the East Suffolk line
and routes in Northern Scotland, But trains are still controlled by
the equivalent of signals - it replaces the physical token which
permitted the train to enter the single track block, and has stop
boards where the stop signals used to be.
The distant signals (yellow) are also fixed boards a convenient
distance before the stop boards. These are protected by traditional
AWS so if the driver doesn't apply the brakes the train is brought to
a less gentle stop,
The driver asks for the token and presses a button to receive it on a
different frequency that doesn't carry speech, after which he is given
permission to pass the stop board and enter the section.
It was introduced after a storm brought down 40 miles of telegraph
line in the North of Scotland and it was easier to use radio between
signal boxes rather than replace the telegraph lines. Initially they
still used a physical token but then it was realised that if they were
using radio then the token could also be sent electronically.
With sprung turnouts at passing points, this was simple, effective and
It is currently being phased out and replaced by the Europe-wide ERTMS
in cab signalling system.
: Certainly got the executives right.
Anybody read Carol Bartzs' comments in Fortune magazine
about being fired from her CEO poition at Yahoo?
I am sure the many employees she terminated said the same
thing about her.
"I like bad!" Bruce Burden Austin, TX.
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