Train scheduling 101 please

[BribieG]

 

Sorry if I'm posting something that must have been discussed frequently but I can't find a recent dedicated thread and I'm sure a good explanation by them wot knows would be very helpful to us newbies.
I travel on the Caboolture line at least twice a week, offpeak admittedly, and here's a typical example from yesterday:

Outbound Nambour express whizzes through Morayfield, a couple of minutes later an Inbound Cattletrain whizzes through Morayfield, then the Outbound Caboolture train arrives, then my Inbound Ipswich service arrives. By the time I get to Petrie I have seen an outbound QR National Freight train, a Sundlander/Westlander whatever, and another Outbound Citytrain (maybe going to be stabled somewhere? seems a bit quick to be the next actual Caboolture train)

Most of this has occurred on a double only track.

Yet whenever the subject of twenty minute or fifteen minute services arises, for some reason there is this huge problem of preventing trains running up each others' bums - London, Paris, even Sydney seem to manage ok so what is the problem here, a quick 101 course would be very much appreciated 

[ozbob]

Others will comment in time.  BUT your experience largely confirms the fact that a higher train frequency is achievable within the present operational constraints.  Same thing happens on the Ipswich line, we regularly have coal trains running in the peak!

Couple of observations by one who knows (another member who wishes to remain anon) for a 15 minute timetable

From the North
Caboolture     Nambour     Shorncliffe     Airport     Doomben     Ferny Grove
4                       4               4               4              2                 4


This equals 22 trains per hour which comes down to 1 train every 2 minutes and 43 seconds.
The only section where the system has to deal with these numbers is between Bowen Hills and the junction west of Roma Street where
the southside trains branch off to go over the bridge.

From the South and West
Benleigh     Gold Coast     Ipswich     Richlands     Cleveland     Rosewood
4                    4                4              4                  4             2

This gives double frequency services in the area from Northgate to Darra and Park Road.
Again this equals 22 trains per hour which comes down to 1 train every 2 minutes and 43 seconds.
The only section where the system has to deal with these numbers is between the junction west of Roma Street where
the southside trains branch off to go over the bridge and Bowen Hills.
Brisbane is lucky in this respect as it is fairly well balanced north and south of the river.

This traffic level can be handled as most of the peak flow area is serviced by multiple tracks in each direction and in fact, with proper planning of schedules, this could be handled with one set closed if it was necessary for track or other maintenance.
The signalling between Bowen Hills is actually configured for a leeway of 2 minutes or less.

Some may disagree on me with this, but the biggest problem in the city is that Queensland Rail run trains that are over crowded and therefore are given excessive dwell or wait times for catch-up or connections.

Running a 15 minute service takes away from both of these issues as a 15 minute wait is not excessive.

[#Metro]

The signalling between Bowen Hills is actually configured for a leeway of 2 minutes or less.

Which confirms for me that metro frequencies of 2 minutes are possible on QR lines currently, or with future signal upgrades.

[somebody]

Frankly, if the constant talk of "it's too hard" continues, I think we should look at going down the Melbourne privatisation route.  Hasn't that been a huge success?

Having said that, I do think they do not want to lose the ability to shut down one of the paths through the CBD to do trackwork on the other.  I think they need to get over it.