> In Victoria, (at least) I have yet to see a speed proving installation that
> shortened headways. The way you shorten headways is to change the track circuit
> overlap/signal spacing.
The original question was about Sydney, which you obviously know nothing about. In
Sydney, with low speed signalling, you can bring trains right up behind each
other. We are now installing conditional clearing signals, which are at stop until
the train is nearly stopped, then they go to caution.
> Of course the most ridiculous speed proving installation was on the Western
> line CTC where you had to "prove" your speed when going into a loop, all
> sounded nice on paper except the trains had no trip apparatus!
But nothing to do with Wynyard.
> 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. There are a few exceptions on the system where the
speed sensing is out, and you need to nearly stop before the trip arm goes down,
but generally they are pretty uniform.
> David, if you were a driver you would know how stupid speed proving is, it does
> not increase safety and it only raises the irritation factor for drivers.
Perhaps we should ask Craig Dewick his opinion then. He is the only one in the
newsgroup (that I know of) who is qualified to comment on Sydney's system. You
certainly aren't.
-- David Johnson CityRail Guard trainman@ozemail.com.au http://www.ozemail.com.au/~trainman/