Re: Melbourne frequencies

[cmgord@ecr.mu.oz.au (Christopher_Martin GORDON)]

: 3.  Running line restraint (ie. single line sections, junctions, etc.);


Just look at a section like Mooroolbark to Lilydale it takes 5 minutes,
so say a down train leaves Mooroolbark at 12:00 it will arrive at Lilydale
at 12:05, the say an up is waiting to leave from the other platform at
Lilydale and it leaves at 12:07 it will arrive at Mooroolbark at 12:12
so the next down could leave Mooroolbark at about 12:15 (if you are using
only the one platform at Mooroolbark).  So you have a 15 minute service
at best, but it abything goes wrong then the whole serivce on the single
line geos wrong and you would have to terminate a train at Mooroolbark
to get things back on track.  

That is why in peak hour you have Mooroolbark trains, that way you have
a 16 minute service to Lilydale 8 minute service to Mooroolbark then
after Ringwood 4 minutes.  If you had trains starting at Ringwood and
stopping all to Box Hill (with the trains from Lilydale and Belgrave
running express) you would have a 2 minute service between Ringwood
and Blackburn.  That is too tight for current set ups.  

You do have little things like the up signal into the platform at 
Nunawading will clear to red/yellow as soon as the pervious
train clears just past the level crossing at Springvale Road.  So the
previous train has only just cleared the platform at Nunawading and the
next train can enter at medium speed.  With normal three sopition signalling
(ie non speed signalling) the signal would clear to yellow/red once
the previous train was about 1/2 way to Blackburn.

This same set up applies to up trains entering Laburnum and the signal
first clearing to red/yellow (then yellow/red after the train is 1/2 way
to Box Hill).

This also applies to stations like Glenferrie, Hawthorn, East Camberwell
on both the up and down lines (but no the center line)


For more detial you will have to wait for me to write my book.




--

Chris Gordon
http://www.ecr.mu.oz.au/~cmgord

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