The Belair Timetable may probably only be an interim timetable till the whole network is once again operating at full capacity. Then things can be sorted out line for line so to speak and tweaks made as necessary to certain timetables. Once the Electric trains start running in full on the Seaford line then these timetables will more than likely be tweaked again to reflect connections etc. All the timetables have to work into one another a bit to allow connections to be made at Adelaide if you so wish. Not sure if I am right on this but it seem's that way to me.
It has already
been confirmed that this is a temporary timetable, lasting only until the Wayville station is opened next year.
My guess is that it is also doing double duty as a test to see whether the staff are capable of delivering intense timetables over a sustained period of time, using expendable Belair line passengers as guinea pigs (daily usage at Glenalta, Pinera and Belair combined is probably just a 150-200 people a day at most) before trying it on two lines concurrently in a year's time when electric service starts. If they can't handle this Belair/Blackwood timetable, then the targeted 9-10 trains per hour each way on the Seaford/Tonsley line might need to be revised downwards and capacity enhanced (using two electric units coupled) instead of frequency.
You must be on the wacky tobaccy if you think that connections between the different lines in the city is ever going to be a consideration for timetabling, as the historical trend of the last ten years on the public transport network has been to abolish connections and countering that would require prioritising the needs of the customers over what's convenient for playing trains. We're already importing a lot of stuff that we've never had on our rail network before with all the work on the Seaford/Tonsley lines, putting out a tender for the import and implementation of a customer service ethic would be one step too far.
As for improving it when the whole network is operational, that could be little than a joke. With slight hindrance of a TSR through Kesville etc the line should be at full capability right now. Presumably (hopefully) never again will there be such a lack of competition for platform space at ARS.
If they can't run a real timetable with a small TSR and 1/3 of the network not accessing the main station there is little hope for them in the future when Seaford et al are landing a three car spark in there every 15 mins.
The TSR through Kesville and Goodwood is probably not much of a hindrance for a Belair service, once all the works are over next year they'll have a higher top speed but they will need to stop at the station.
EMUs will need to be arriving or departing Adelaide at an average of three minute intervals in the peaks to meet the various service promises that have been made about the Seaford/Tonsley line out of Adelaide. A 15 minute frequency to/from Tonsley is just the latest addition, a departure or arrival every 5-7 minutes at Seaford in the peaks has been promised as well as an average frequency of 7.5 minutes for the Seaford/Tonsley line in the peaks, which is eight trains per hour.
That's a minimum of nine trains an hour in each direction to fulfil all three promises (or 10/8 or 11/7, the "departure or arrival every 5-7 minutes at Seaford leaves a little flexibility) which is an intense service by most measures, and one I'm not confident our signalling system or staff competency is up to handling. Hence my comment further up about trialling an intense single-line service on a handful of expendable users before doubling everything and trying it on thousands.