Can they issue an Order while the Train in running as it approaches a 'Location' to be able to proceed into the section ahead or must it be stationary or are the Orders 'flexible' so that they can issue one to go from A to C if the section from B to C is clear?
Train Order issued to proceed from A to B and on arrival at B, a new Order is issued to proceed from B to C with the Order from A to B now cancelled or can they now if the area between A and C is clear, issue an order accordingly?
You could take your Order on the run, and I regularly did so when working west to Dubbo. The only catch was, on the 81's, the majority had the CountryNet handset to the left of the Driver, so if you were the Fireman, you either ended up garrotting your mate, or ended up doing as I did, sitting on the inspector's seat to take the Order.
I don't believe they can issue an Order from A->C, and approaching B, give you a new Order from A->D. Much easier to give you a consecutive Order from A->C and then C->D. You can have multiple valid Order's issued to a train, but only one of those Order's is currently "active" so to speak. The rest are for sections in advance.
The problem with traditional Train Order safeworking was that there was nothing to prevent the Train Controller from issuing conflicting orders, other than his memory aided by a manually compiled graph. Looking from a risk management perspective, TO systems were an Administrative control, (very low on the 'Hierachy of Controls'); effectively a system induced accident waiting for a time and place to happen.
What provision is there in the new crop of TO systems to prevent the Train Controller issuing conflicting orders?
Not quite...When you fulfilled your TO, the system either electronically blocked the track where you were standing (for a TO to a Yard Limit Sign), or if you fulfilled your order within Yard Limits, the "system" asked the Train Controller what roads were occupied, so if you were on the Main at B, the system wouldn't allow a TO from A -> C.
That being said, it came down to the Train Controller accurately specifying what roads were available for traffic, and it very nearly failed catastrophically one night when the XPT was given a TO through Manildra (IIRC) with a wheatie standing on the Main after fulfilling his TO and the Controller didn't block the right roads.