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South Korea

Area code 82 Common abbreviation ROK Last updated 11-2-2018
Road class Syntax explanation Administrative subordination Sub classes Zones System Remarks
Asian highway A[0-9]<1-2> Asia See Asia
Motorway [0-9]<1-3> national 1 main north-south road Arterial routes
[1-6][05] grid
[1-6][1-46-9] Subsidiary arterial routes
[0-9]<2>[1-4] derived from 2-d numbers Branch roads
[1-9]00 derived from postal code areas Metropolitan belt roads
National road [0-9]<1-2> national 1-d grid
Local road [0-9]<2-4> national 2-d Nationally funded
3- and 4-d Provincially funded
Metropolitan road [0-9]<1-4> municipality
General description:
Motorways: A new grid system has been designed which can be extended to North Korea.
Route 1 is the most important one linking the capital Seoul to the second largest city Busan in the southeast.
2-d numbers form a grid with even numbers for east-west routes, with numbers increasing to the north, and odd numbers for north-south routes, with numbers increasing to the east.
Even numbers from about 70 are reserved for North Korea. Existing north-south routes could be extended to the north as well.
The most important north-south routes have numbers ending in 5, important east-west routes have numbers ending in 0. These are called arterial routes. Most other roads with a 2-d number are only planned so far. These are called subsidiary arterial roads.
There are three kinds of 3-d numbers: those ending in 1-4 are so-called short-distance branch roads. They are derived from 2-d numbers by adding a digit at the end, for example 45 > 451. The last digit is odd for north-south roads and even for east-west routes. A special case are numbers ending in 0 but not in 00: routes 110, 120 and 130, which all lead from Seoul to the west. These are not derived from 11, 12 and 13 respectively: 11 and 13 do not exist, but could in principle be in the area in question, but route 12 is in the south. They may be derived from number 100. More appropriate numbers would be 152, 154, 156, or 502 etc.
Metropolitan belt roads are ring roads with a number ending in 00. The first digit is the postal code region number (e.g. number 100, postal codes near Seoul have first digit 1).
Other roads:
National roads with odd numbers generally run north-south and those with even numbers are east-west routes. 1-d numbers form a grid with odd numbers 1-7 increasing to the east and even numbers 2-6 increasing to the north. There are many exceptions for 2-d numbers. There are no zones, but the higher the number, the more to the north the road is (99 is an exception, on the island Cheju).
Local roads have a 2-digit number when they are funded by the national government, and a 3- or 4-digit number when they are provincially funded.
Metropolitan roads have 1- to 4-digit numbers and exist in Seoul, Busan, Daegu and some more cities. In Seoul they are classified as Special metropolitan roads and their shield has a red bar, see below.
Road signs: All signs used to be blue, but nowadays most signs are green with white text. There does not seem to be a relation between color and road class or type.

Road class Shape
Asian Highway
National road
Provincial road
Metropolitan road Standard, e.g. Daegu
Seoul (special)
The new motorway numbering system was introduced on 24 August 2001. The old system had sequential numbers which were assigned in chronological order from 1 to 23. Number 1 is still the same, all other numbers have been changed. There were some derived numbers with suffix '-2' (e.g. 19-2), and the ring around Seoul had number 101. Numbers 1-8 were even for east-west routes and odd for north-south routes, but numbers 9 and higher did not satisfy this rule.
There used to be a system of Local roads with numbers between 300 and 1150. Zones were determined by the first digit of 3-digit numbers and by the first two digits of 4-digit numbers as follows:
3 Seoul area
4 Northeast
5 Kangnung area
6 West
7 Between Taejon and Kwangju
8 Southwest
9 Taeju area
10 Southeast
11 Cheju
Odd numbers generally run north-south and even numbers run east-west but there are many exceptions.
Note that the system can be extended to North Korea. National roads 1, 3, 5 and 7 would continue, number 8 would be Pyongyang-Wonsan. 2-digit national road numbers would be between 57 and 99. For local roads, zones 3 and 4 could be extended to the north and zones 1 and 2 could be added.
There used to be hexagonal shaped road numbers (black digits on white) but these are apparently obsolete.
Sources and links: various maps and atlases and websites

    Official sites:
  1. Korea Highway Corporation
    Other links:
  2. Roads and Expressways in South Korea Wikipedia
  3. National highways of South Korea Wikipedia
Marcel Monterie