Road Stacking Limits

[HMCS Rosthern]

The Road Stacking Limit is the maximum number of men or equivalent that can travel via Road Movement through a hex. It is also the maximum number of men or equivalent that can travel via Rail Mode through a hex.


Stacking Limits
Road: The maximum number of men, or equivalent in men, that can move using Road Movement.
Maximum: The maximum number of men, or equivalent in men, that can stack in a single hex.
Towed Gun: The maximum number of men, or equivalent in men, of
Towed Gun units that can be deployed (non-Travel Mode, non-Rail
Mode) in a single hex.

If I move a single unit in travel mode along a road it can never exceed the RSL (cuz it aint a stack)
If I move >=2 units in travel mode along a road whose strenghts exceed the RSL, road movement rates do not apply.
If a single unit or stack of units in travel mode encounters a stack or single unit in travel mode that exceeds the RSL, it can not enter the hex by road movement. (BTW Can't cross a bridge). This is why convoy of units get strung along roads in travel mode.   

But what about stacks of units not in travel mode and their impact to the RSL? 
The rules say that the total stacking value in the current hex can be found in the center of the Terrain Info box by right-clicking in the Hex Info Area and if that value has an "X" the RSL is exceeded.
If I  highlight all stacks of units on the map that exceed the Road Movement stacking limit view -> Highlight -> Road Stacking Limits it's showing those hexes with the X.   

How do stacks NOT in travel mode impact road stacking limits? I observe that these stacks are sometimes highlighted.
What value is used to compare against the total stacking value of the stack?
is it the parameter data? For example:
Stacking Limits:
    Road: 350 men        Maximum: 1500 men

[ComradeP]

Stack size checks of any kind always use the total number/strength of units in the hex or moving into the hex, regardless of whether they move in T-mode or not.

If there's any kind of unit in the hex in normal/Deployed or T-mode and a unit or stack moves into the hex, if the total number of men (equivalent) that would be in the hex after the move is higher than the Road movement limit, a unit can't use road movement to enter the hex.

In difficult terrain or poor weather conditions, you need to move units off the road. In normal conditions, clear hexes are not much of an issue, particularly for (half-)tracked vehicles.

Rail movement is possible as long as the move doesn't violate maximum stacking limits for units in rail mode. A unit can't switch from rail mode to T-mode (/leave rail mode) in a manner that would violate the maximum stacking limit.

Overstacking hexes, excluding a combination of units in rail mode and either T-mode or normal/Deployed mode, is possible through reinforcements or units regaining strength.

[76mm]

These stacking limits are mainly an issue at night, where if you don't use road movement rates a moving unit can get disrupted.