Road designation

A road designation and a road name abbreviation are easy ways to refer to a road.

The road designation can be created from the original road name or constructed from the road type and number. Road designations are used especially to have a non-ambiguous system of labeling roads on maps and road signs.

Letters are often used in road designations to indicate a class of roadways. Within such a class, roads are distinguished from each other by a road number. The way such letters are used depends on the country or other political jurisdiction which contains and controls the road. For instance, among A1 motorways, the one in Spain has a hyphen between the A and the 1 (Autovia A-1) while in Germany the Autobahn 1 is written A 1, with a space between the A and the 1. In Argentina there are zeros between the A and the 1 (Autopista A001).

Depending on the country, the letter attributed to a road may be part of a road grading system, be a shortening for a type of road especially in a foreign language or refer to a geographical zoning system, such as the Appalachian Development Highway System or the county highway systems of California, Iowa, and Michigan in the United States.

M is for primary roads, A for single carriageway interstates, B for secondary highways, C for roads linking small settlements and D for unsealed roads linking very small remote towns.

M stands for "motorway" while A, B, C, D are grades of roads (most important first) and U means "unclassified". However C, D and U are not used in road signs.

G stands for national highway and S is for provincial roads. X and Y are for local roads between counties and villages.

A stands for motorway and B is for main roads. E and F are for smaller local roads.

T is the prefix for all roads, however not represented on route shields. The prefix is mostly only used by the Estonian Road Administration and is not in common usage when referring to roads.

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Wikipedia