I'm sure I have commented on this before, but I've always liked the convention of using the blue signs over the collector lanes and the green signs over the express lanes. I think it makes more sense than the MUTCD system of using the same color for all guide signs and then mandating extra banners on top of the signs to ensure the dumbest drivers out there understand that a sign over a different carriageway is directed at people on that carriageway.
What are the chances that the MUTCD might one day allow this sort of signage? I too think it's genius, and would love to see it implemented into the manual.
The funny thing is, if you actually mentally think about it, the places which do have an express-local type of setup. (I never liked the term "collectors" too much, it does make sense to us roadgeeks, but I think local sounds better) I can only think of a handful off the top of my head, all seem to do it drastically different. The one outside my own backyard that I am most familiar with is the one on I-96 in Detroit.
The only thing I would like to see, even though it's my own nitpicking, is the 401 collector to express transfer east of Dixie somehow acknowledging that you must move to the express to stay on the 401, some would argue this part is not part of the main express-collector system. Remember that signs on the 403, and now signs on the 401 around Mavis Road acknowledge this as an express-collector system now.
As for blue guide signs, while within the GTA, any situation that resembles an express-collector system gets blue signs, such as on the 404, 400, the Gardiner, and parts of the 403. (NOTE: Hwy 403 signs in EB Collectors that show the diagram sign for Hwy 410/410 and the exit only signs are still green when they should be blue) However, they are nowhere to be found on the Conestoga Parkway in that area around where the Hwy 7 exit is, when that has a short express-collector system.
You may say that's short, well so is the one for the Gardiner, and especially, Hwy 404, but why do those have blue signs while the one in the Conestoga Parkway does not.
Sure I like the idea of different carriageways having different colors, but where do we draw the line, in Greater Buffalo close to the Lackawanna Toll Barrier on I-90, there is something that does resemble an express-collector system there, should the signs in the outer carriageways get different colors than the mainline? As I recall, the outer carriageways go to US-219.
These are some ramblings by me.