Road accidents claimed 27 lives and injured 201 people on the first day of the seven-day Songkran holiday travel period, officials said on Saturday.
A total of 211 accidents were reported on Friday, the Road Safety Operation Centre said, as people began travelling for the Thai new year holiday.
All of the figures for Friday were below those from a year ago.
Driving over the speed limit was the main cause of the accidents, accounting for 41%. A quarter of the accidents involved cutting in front of another vehicle and 23% were related to drunk driving.
Mukdahan recorded the highest number of accidents at 11 and injuries at 12, while Bangkok had the most deaths at five.
Motorcycles were involved in 84% of all accidents, with pickup trucks and cars at 5% each.
Main roads accounted for about half of all accidents, and the period between 3pm and 6pm was the peak for accidents.
Some 276 drivers were arrested on Friday for driving under the influence of alcohol, or about 85% of all arrests, a slight increase from 258 on the first day of the safety campaign last year.
Driving under the influence of narcotic drugs came second with 47 cases, followed by three careless driving cases, he said.
