Ah... I noticed that the "ends" of roads are a tad strange, but that's still bizarre. The terrain underneath the various pieces is/was as follows:
~~~~~ ~~~~~~~ ~~~~~~
forest river+resource city
clear ~~~~~~~ ~~~~~~
So what you're saying is that an army that can normally move over anything but a peak, cannot enter a road/resource from a forest even though it would normally be able to move from a forest to a river if the road/resource wasn't there.
This bears out as I ended up building an air base on the clear terrain - something that has an 'implied road. After that the army could move from the forest to the air base and then into the resource. This raises the question of why a transition from forest => air base (implied road) is different than the transition from forest => resource (implied road). First one is OK, second one isn't.
As an experiment I disbanded the air base and attempted to move from the clear into the river+resource... and still couldn't... so, (having disbanded the air base that used to be on the clear, I built a road segment there... and then the units could move into the river+resource without problem. I have to consider this strange behaviour because I've never had trouble leaving or entering a road somewhere in the middle of it -- although I learned that you have to start/end a road on terrain that the unit is actually capable of moving on... but in this case, road or no road, hidden or not, the units should have been able to move on that terrain.
One could become EXTREMELY frustrated with this sort of hidden behaviour.
Is this road or resource beginning/ending behaviour documented anywhere? I've read the manual more than once (but don't have it memorized! :-)
Thank you, very much for this explanation!
Sincerely,
Gary
PS: Interestingly enough I found a very similar situation at another place in the game where an army that I'd directed to go from A to B (about a distance of 15 - mostly clear terrain - was still trying to get through a choke point that was blocked by a developed resource. It would continually oscillate back and forth trying to get through. I discovered it some 100 moves later after wondering why it hadn't reached it's destination yet.