It should have been pretty obvious that even with 5 types of vehicle you can't make up enough small and large trains to meet CL's current agenda. And as for "types", we're really talking about changes - mostly relatively minor - to the internal fitout, and a properly speced train would allow these to be changed to meet changed timetable needs relatively easily.
Likewise, if I was to factor in other options, I can the Overnight services, for example, Syd-Mel and vice versa would be say a 6-7am start and just after lunch, but this means you need for trains instead of current 2. Pax trains get priorty during the day, freighters get a free run at night, fair compromise me thinks and makes it easier for O/N door to door to be achieved. I'd also run at least 2 dailies to Brisbane, but thats another complex issue again. If you can cut the overnight trains, you cut the number of cars from 6 to 5, but better still, you cut the lead driver cars from 2 to 1, saving probably 1 car in costs. But at plus 60 cars, 6 different cars is not a huge drama compared to CL's current status.
Not all obviously, but a lot of CL's destinations are a 12 hour journey (if you include the coach connection). For a day service that's basically 8am to 8pm. An hour or two either way and you have either a terribly inconvenient departure or arrival time. For example, a just after lunch 1pm departure from Syd means an arrival in Mlb at between 1 and 2 am. I know it probably should be about an 11 hour run, but it isn't. And quite frankly midnight isn't exactly a great arrival time either, as door to door you're turning up at your host's house in the wee small.
I'm of the view that 2 appropriately sized trains per route is about right. For the 12 or more hour runs that's 1 train a day each way. Places like Dubbo at ~8 hrs would get 2, Canberra @ 5hrs 3. An advantage of a DMU fleet is it's easier to reduce capacity to the extremity of the network without compromising frequency to the inner part. For example, the NCL with a DMU fleet could operate 1 train to Grafton that splits, half going on Brisbane and the other half returning to Sydney as a red eye, complemented by a mid north coast train running UP-DOWN. That gives the mod-Nth coast 3 trains a day: morning, afternoon and night (as per now). Far Nth coast gets a day and night train (vs a very late and very early day train plus a red eye). That required a fleet 5 DMUs vs the 5.5 XPT units for the current timetable.
A viable minimum seat number for a DMU is also probably ~200 seats, but depends on a number of factors.
Luggage, checked luggage must be an option, but you can provide options to reduce the amount. CL wouldn't check in our stroller, policy, they will not touch baby things! By reducing the doors on each car from 4 to 2, you can use the vestible space (which is the crush zone) as bag storage.
People have luggage, and the further they travel the more they tend to have. That's a fact of life. From a fleet management/design perspective - no checked luggage would mean sacrificing a row of seats per vehicle (assuming it was built for purely long distance runs and not commuter runs as well) for more PAX luggage space at the expense of a dedicated luggage area.
That's the least of my issues with checked luggage, there are a lot of good reasons to ditch it IMHO - not least because in the era of wheeled suite cases very few PAX are not capable of handling their own luggage these days.
I tried to reduce the number of types, but the buffet I had to have in two types of cars. If you look at the RTT, I believe it has two, cars 2 and 5. I think a 4 car train is the limit of the single buffet train. Otherwise there is too many people walking past those seated near the buffet.
Well the XPT has 1 large buffet, but it's usually staffed by 2 and there is a queue from second class and another shorter queue from first class .
I'd have thought the buffet should be a profit centre for train operators, but they aren't. But again, talking up space in the train while it is an issue, probably isn't a big one.
If you view the primary competition for delivering regional PT services as busses, this is another advantage road coaches have: they can naturally off-board their catering.
FC me thinks must be booked seating, EC, mmm. I'd like to say they should have option to show up and ride, ie stand until a seat is available. But there are issues with this. I think in 21st century with booking possible as the train is actually in service. ie book a seat 5min before arrival using your iphone, but 5hr after it intially departed is not a big issue. I think there is also sufficent demand for most services to have two levels of seating. CL should also have option to upgrade regular users to FC when numbers are low to enable more EC tickets to be sold.
The difference between FC and EC service standards in CountryLink is trivial. The only real difference is whether or not you're sitting next to a government or self funded pensioner.
And yes, there are advantages to the operator to being able to offer price differentiation. I would argue that occurs already even within EC on CountryLink.
Where FC/EC costs is you need to have allocated seating. It means you need all the infrastructure to book seats, allocate seats/re-allocate seats, check people are in the right seats etc, and for what? Again, this is not an issue busses have to deal with in the country.
There probably does need to be a mechanism to ensure a train isn't 200% oversold, and a way for travel agents to sell tickets. But that isn't the same as allocated seating.
Anyway, if you go with my agenda of no allocated seating, no checked luggage and if possible off-boarded meal catering, the fleet type requirements drop to 2: cab and non cab.