This still occurs. This can be seen in action in the same save game as last; at Queensinglow, there is a bridge and a section of dual carriageway, where buses are stuck with "waiting for clearance" and indefinitely immovable.
(http://i.imgur.com/sehZpus.png)
Each time the map is reloaded, one vehicle will depart, but the rest will still remain waiting indefinitely as if they are awaiting clearance.
No one has looked into this yet?
Apologies: I have not had a chance to look at this one yet. There is nothing inherently wrong with road vehicles awaiting clearance: that is not by itself incorrect behaviour: they will do this when the next tile is blocked, or when there is no free stop beyond a choose sign. Is this a situation in which they are reporting "waiting for clearance" when there is a free stop tile beyond the choose sign?
They stop at one-way road signs, not chose signals; they treat all road signs as if they were awaiting clearance. This can be observed at the site mentioned and pictured in the before posts. The vehicles will stop at one-way signals, and await clearance, presumably for their ultimate destination (as it seems to permit only a single vehicle to be in motion at any one timne, as if it as a section of single-track railway). The chose signals occasionally don't work right either, only permitting one vehicle at a time, but not sure if this is reproducible easily; this should be.
My apologies for the delay. I think that I have found and fixed two related issues causing this behaviour; would you be able to re-test? I should be grateful.