Covering 4,930 kilometres, these routes will go in the North-South and East-West directions.
The North-South route will cover 1,600km from Chiang Rai to Songkhla, 490km from Nong Khai to Laem Chabang and 470km from Bueng Kan to Surin.
The East-West route will cover 710km from Tak to Nakhon Phanom, 880km from Tak to Ubon Ratchathani, 310km from Kanchanaburi to Sa Kaew, 220km from Kanchanaburi to Trat and 190km from Phuket to Surat Thani.
Transport Minister Saksayam Chidchob said the transport office will draw up details and design these eight routes before studying investment methods to see if public-private partnership is appropriate or if other methods should be considered.
He added that these routes must run in straight lines and avoid cutting through community centres.