It struck me, that it might be desirable to add the cost of man power required to operate convoys.
Many railway operators look at ways of reducing operating costs and one way of doing that is reducing the amount of people required for operation.
Take for example a steam engine hauling pax. You need a minimum of 1x engineer, 1x fireman and 1x conductor to operate it. If it's a double header, then 2x engineer, 2x fireman and 1x conductor are needed.
On a diesel or electric locomotive with remote control, you would only need 1x engineer and 1x conductor.
There are even further cost saving incentives with one man operation and unmanned operations.
Currently, it is not so hard to include the costs of man power for single locomotive as maintenance, but this does not scale well when they allow operation in multiple formations. Likewise, the cost of a conductor does not change whether he has to attend 4 carriages or 8.
Yes, I had considered this. The cost of a guard can be dealt with simply by increasing the fixed maintenance for guard's vans/brake vans, and that is straightforward enough. For locomotives working in multiple, specific code would be needed, I think. This would need some careful thought and is not currently a priority. If somebody could write a patch to allow for this and represent what is happening clearly to the player, then I should be interested in including it.