Well despite ruling it out here is a simple staff instrument simulation. How it works is by naking one divisable staff, or a 2 part staff. This would allow two train to travel in the same direction. How it is done is to wire two different plugs together. This will stop the wrong part of a staff to be used to falsely activate a section. To be pedantic if there are several staff, one simply uses different plug types so no two sections are compatible (as per real life practise)
Having the same staff type for connecting sections would be dangerous as one might put the wrog staff in the wromg machine. So the real railways has differnet patterns for their staffs. And they had their stations they served engraved on them as well. All part of the need to make the system be as safe as possible.
Full size staff machines can hold more than one staff.So when a train arrives at the other end, it can 'sink' tbhe staff into it allowing the other end to issue another staff. So more than 1 train can proceed in one direction, until all staffs are gone. Otherwise they work much as we have shown here, since most train on the line will balance the staffs between each end. But there have been instances of having a 2 part staff, what I'm "modelling" here.
The photo on the left shows a Western Australian Staff Machine. You can see there are severak staff within the machine. And there is a loose staff, so that must mean the section is occupied, well it was until we put this into the machine, making the section clear -this was on the Bennet Brook Railway just North of Perth.
So how it works:
* If the staff is not in the staff machine, one cannot proceed. * If the staff is in the staff machine, and you are the only train to go in that direction, you take the whole staff. This turns on the occupancy light warning anyone that the section is occupied. When the train gets tot he destination, you plug the staff into that staff machine setting that machine to unoccuplies with no light on.
The proceedure is similar with two trains going the same direction. The first train takes the plug out but leaves one part of the staff plugged in. The operator takes the 2nd part of the staff - this gives the first train authority to proceed, even with the light now showing occupied. When the first train reaches the other end it puts the first part of the staff into the machine and continues.
Meanwhile the 2nd train is ready to enter. It takes the 2nd part of the staff and proceeds intot he section. With no staff in the machine, no other train can proceed. When this 2nd train reached the other end, it inserts the staff fully into the machine, releasing the section, which is now available for travel in the other direction.
Like other ideas, one could make it turn the Greytown-Costerfield into one super section. And like the other systems, the home and starter signals are under the control of the station operator though the starter only applies to any loco with the staff ! If there is no staff, the starter ony means the train can shunt within station limits before the home signal.
It is a working staff system. Each panel would have the occupancy light, the socket for the staff, and a dummy spot to put the half a staff when dividing it. I'd locate them at the end of Costerfield and at the end of Greytown. Ideally I'd have a mimic panel for the station operators to see if the section is occupied or not.
And again the system could be used for theNinamanina branch as well.