Which states have reference markers (and what do they mean)?

[empirestate]

(Intending to compile this information into one place...)

Which states have some kind of reference marker or similar device posted on public roads, bridges, etc.? What information do they contain, and how are they interpreted?

By "reference marker", I mean something more specific than mile markers (there's already a thread for different states' use of those). Reference markers would be used mainly for internal purposes, such as location referencing, data recording, or inventory. Many states will have implemented them as part of an LRS program (linear [or "location"] referencing system). They will typically display a route number along with some other location information. Also in this category would be things like California's structure identification signs, which pertain specifically to overpasses, bridges, etc., but also contain the route number and some location information.

Tell us about your state's system, and post any links to existing threads or other information.

My state, New York, probably has the most high-profile system of reference markers:
https://www.aaroads.com/forum/index.php?topic=6842
https://www.dot.ny.gov/divisions/engineering/design/dqab/rmm

Vermont has a similar system, at least in appearance:
https://www.aaroads.com/forum/index.php?topic=6752

Pennsylvania has segment markers as part of its LRS:
http://www.dot.state.pa.us/public/PubsForms/Publications/PUB%20664.pdf

What else?

[hotdogPi]

New Hampshire has some, but very little is known about them.

[empirestate]

New Hampshire has some, but very little is known about them.

Well, what's the little that is known?


iPhone

[Scott5114]

Oklahoma DOT has three-line ones, which are often placed on the backs of stop signs along a state highway, and at other places like bridges over streams. They are of the format:

44
19
3.13

Which means: county #44 (alphabetically, Adair County is 1, Woodward County is 77, 44 = McClain County)
control section #19 (each control section is a segment of road numbered uniquely within that county only, which typically follows a numbered route but ends at some junctions, always ends at county lines, and often ignores concurrencies)
3.13 miles from the south/west end of the control section