Turkish State Highway System

Devlet Yolu
Route markers for three Turkish State Roads
System information
Maintained by Karayolları Genel Müdürlüğü
Length:	31,106 km (2016) (19,328 mi)
Formed:	1950
Highway names
Devlet Yolu:	D.XXX
System links
Turkish State Highway System (Devlet Yolu) List

The State Highways of the Republic of Turkey (Turkish: Türkiye Cumhuriyeti Devlet Karayolları), abbreviated as T.C.K. are an integrated network of highways and roads in Turkey, consisting of a numbered grid spanning across the country. They are more commonly called State roads (Turkish: Devlet yolu) and are the primary road network in Turkey. The network is mostly maintained by the General Directorate of Highways (KGM), except for within large cities (Turkish: Büyükşehir) where the respective city municipality assumes responsibility.

In the early 21st century, the network was greatly expanded to accommodate four-lane highways throughout the country. As of 2017, 19,790 km (12,300 mi) of the total 31,106 km (19,328 mi) system are four-lane highways.

Unlike motorways in Turkey, state highways do not have a minimum design standard. Despite the majority of the system consisting of four-lane, dual highways, other routes can be two-lane highways or even dirt roads, in mountainous areas. Some routes, especially within major cities, have been upgraded to controlled access highway standards; while other routes, such as the D.650, between Arifiye and Bozüyük, and the D.200, between Eskişehir and Ankara, consist of minimal at-grade intersections. Bridges and Tunnels are common among the system, yet not as plentiful as on motorways.

All state highways have a three-digit designation preceded by a D. The system is numbered based on direction and location. Route numbers range from 010 to 977, while 010 to 490 are east-west routes and 505 to 977 are north-south routes. Even-numbered routes generally run north-south, while odd-numbered routes generally run east-west. The only exception to this rule are four north-south routes, D.550, D.650, D.750, D.850 and D.950, that have even-number designations. The second criteria is based on the geographical location of the route. For north-south roads, routes in the west will have lower numbers, while routes in the east have higher numbers. For east-west roads, routes in the north will have lower numbers that get higher towards the south.