Thai highway network

The Thai highway network follows the left-hand traffic rule of the road. The network is the twin responsibility of the Department of Highways (DOH, Thai: กรมทางหลวง, Krom Thang Luang), and the Department of Rural Roads (DORR, กรมทางหลวงชนบท, Krom Thang Luang Chonnabot), under the oversight of the Transportation ministry of Thailand. Public highways (ทางหลวง, thang luang) are also called public roads (ถนนหลวง, thanon luang), especially when part of urban streets. The network spans over 70,000 kilometers across all regions of Thailand. Most are single carriageways. Dual carriageways have frequent u-turn lanes and intersections slowing down traffic. Coupled with the increase in the number of vehicles and the demand for a limited-access motorway, the Thai Government issued a Cabinet resolution in 1997 detailing the motorway construction master plan. Some upgraded sections of highway are being turned into a "motorway", while other motorways are not being built from highway sections.

The 1992 Highway Act (Thai: พระราชบัญญัติทางหลวง พ.ศ. 2535), revised as the 2006 Highway Act (Thai: พระราชบัญญัติทางหลวง (ฉบับที่ 2) พ.ศ. 2549), defines the following five highway types:

A special highway (Thai: ทางหลวงพิเศษ) or motorway is a high capacity highway designed for high speed traffic, for which the Department of Highways carries out construction, expansion, upkeep and repairs, and is registered as such. Motorway entrances and exits have controlled access, and controlled by the DOH. Registration of motorways is overseen by the Director General of the DOH.

...
Wikipedia