Now for a signalling 101 course for the paid passenger.
<<<<<<<> One of speed proving's many problems is that it has to be set for the
train
> with the worst braking rate,in the worst conditions, (rain etc) this means
that
> trains with better braking rates can and do get tripped when operating
> normally.
Garbage. The speed is fixed, regardless of the train type. This way, the
driver
knows if he is doing a certain speed, he will not be tripped. Braking rates
are
irrelevant, as it is the driver's responsibility to reduce the speed of the
train
before the low speed signal. >>>>>>
I did not infer that the speed proving speed was not fixed. (its a good idea to
read and understand someones post before shooting your mouth off) When the
engineers design a signalling installation they get graphs of deaccelartion
rates for the "worst braking" trains. They base all of their calculations on
the "worst train" On lines that see nothing but suburban trains they may base
their calculations on "good braking" trains but in this case there will be a
very low speed limit for diesel hauled trains, (such as the ocassional ballast
train.)
Braking rates are VERY relevant. If the speed proving is set so that our "worst
braking" train will get tripped doing 10kph (or whatever speed) it follows that
a better braking train could be doing 20 kph, easily able to stop at the
signal, but still get tripped. To spell it out more clearly: You can get
tripped even though you are within the speed limit and have your train under
complete control.
You mentioned that: "This way, the driver
knows if he is doing a certain speed, he will not be tripped." Great, lets say
there are a couple of hundred speed proving trips installed, all set at varying
speeds, you expect a driver to remember each and every one? Drivers have enough
to remember without adding to it.
If you ever qualify as a driver what I just posted will make a lot more sense
to you!
Mark.
THE ROCK is dead
Long live THE ROCK!