Land developers will be required to include traffic impact assessments in their projects after TIA criteria, expected to be finalised this July, come into effect.

Land developers will be required to conduct Traffic Impact Assessments (TIAs) to try and relieve traffic congestion caused by their projects when TIA criteria, expected to be finalised this July, come into effect.

Within two years, "TIAs will work in tandem with Environmental Impact Assessments [EIAs]," Sarawut Songsiwilai, head of the Office of Transport and Traffic Policy and Planning, said on Monday.

Developers of mega-projects likely to harm the natural surroundings are currently obliged by law to conduct EIAs, to explain ways to mitigate possible unpleasant impacts.

They will now be required to provide a TIA report in the same vein if their development projects, especially those in cities, appear to worsen local traffic flow.

New department stores, markets, stadiums, schools, universities, large conference halls, office buildings and bus terminals will all be up for TIAs, according to Mr Sarawut.

He was presiding on Monday over the second public hearing on TIA criteria, being drafted by his office.

Opinions will be used to improve the draft, which is scheduled to be presented at the last public hearing in early June.

"We expect to finish TIA criteria by July and will forward it for further approval," Mr Sarawut said, adding the cabinet will have the final say.

Traffic volume in areas where new buildings will be constructed will be used to decide whether developers need to assess their traffic impact.

If there are less than 50 cars passing the area in an hour, they are not required to conduct a TIA, he said.

His office is proposing many measures to relieve, or prevent, heavy traffic snarls if development projects are carried out on crowded roads.

Developers of new shopping malls will be required to build a "sky walk" to connect them with mass-transit systems to improve transport in these areas, Mr Sarawut said.