@Imperious:
OK here we go:
All land units starting in a factory space may move double movement only during non-combat movement phase , and this number is limited in quantity to the number of undamaged placement capabilities of that area.
In this way the enemy may interdict and bomb the rail-centers with SBR.
Obviously, minor factories always have less capacity for rail movement.
4 movement points seems high for Mech Inf and Tank.
Throwing some numbers:
All ground units (including AAA, Tank and Mech Inf) can move 3 territories in Non-Combat Move starting from a Factory.
And can move only 2 territories in Combat Move.
So this give +1 bonus move for slowest ground unit such as Infantry and Artillery. And of no use for the Mech Inf and Tank.
The idea of starting from Factory is great and simple.
It allows to cap the number of unit gaining the bonus move with the actual capacity of the Factory or IC.
Also, if it is damaged, it can also affect this railroad capacity.
If 4 moves are acceptable but for very few units,
then I would allow 4 moves in NCM for all ground units (including AAA, Tank and Mech Inf).
And 3 moves in CM for all grounds units. This would represent a +2 bonus for Inf and +1 for Mech Inf.
The bonus move is applied in a simple manner that way.
All units are moving by train after all, there is no difference between putting on board vehicule or people.
They get down the train at the end of the line. That’s it that’s all.