Authorities are considering increasing tolls for two intercity motorways -- Bangkok-Chon Buri and Samut Prakan-Ayutthaya -- to raise funds for new road projects.
This will allow the Highways Department, which oversees the motorways, to gain more revenue and spend it on infrastructure development instead of always relying on the state central budget, said deputy department chief Anon Lueangboribun.
The department is looking into various factors which will be used to determine appropriate new rates that "will not cause too much of a burden on motorists", he said.
The factors include forecast changes in road usage, revenue and maintenance expenses.
"Many agencies have suggested a toll increase to 1.5 baht from 1 baht a kilometre," Mr Anon said.
His department not yet decided as it is waiting for the study result.
What the department is more sure about, however, is that this is an opportune time to increase tolls.
The Comptroller-General's Department, the Budget Bureau and the Office of the National Economic and Social Development Board all back the idea, Mr Anon said.
The Highways Department argues a toll rise can be justified because current tolls have stayed unchanged for 15 years, he said.
As part of the study, the department is looking at how much revenue the various motorways raise.
The Bangkok-Chon Buri motorway, also known as Motorway No 7, was the first intercity motorway in Thailand. Opened in 1998, the 125km route offers another course for drivers who want to avoid traffic congestion on Sukhumvit Road and parts of Bang Na-Trat road on their trip from Bangkok to Suvarnabhumi airport and Chon Buri in the East.
Also opened in 1998 was the Samut Prakan-Ayutthaya motorway, also called Motorway No.9.
It links Samut Prakan's Bang Phli district with Ayutthaya's Bang Pa-in district on a distance of 63km.
The route forms the eastern part of the 168km Kanchanaphisek Road, the Outer Ring Road around Bangkok which connects the capital with Nonthaburi, Pathum Thani, Samut Prakan and Ayutthaya.
The western part of Kanchanaphisek Road starts from Rama II Road and moves to the Thon Buri area in western Bangkok, Nonthaburi, Pathum Thani and Ayutthaya.
At present, revenue gains from the motorways No.7 and No.9 stand at 12 billion baht a year in total, the Highways Department said.
The Samut Prakan-Ayutthaya route appears more popular with revenues as high as 7.2 billion baht, compared with 4.8 billion baht earned from the Bangkok-Chon Buri route.
The new toll rate would further boost the department's coffers and, to earn even more money in the long term, the Comptroller General's Department has suggested highways officials also raise funds through the Thailand Future Fund, Mr Anon said.
The fund, scheduled to be launched by the year-end, is a new financial instrument aimed at raising funds for government infrastructure projects.