The deputy director of the National Road Safety Centre said there were 435 accidents on Wednesday, killing 41 people and wounding 514 others. A third of the accidents were caused by drunk drivers, while speeding and cutting in too closely in front of other vehicles were also factors.

Some 85 per cent of accidents involved motorcycles and most took place on straight secondary roads between 4pm and 8pm.

Chiang Mai and Nakhon Si Thammarat experienced the most deaths with three each, followed by Trang, Nonthaburi, Phitsanulok, Phetchabun, Samut Sakhon, and Surin with two deaths each.

Udon Thani had the highest number of injuries at 23, followed by Nakhon Sawan, Buri Ram, and Si Sa Ket with 19 each.

Si Sa Ket and Udon Thani had the most accidents with 19 each, followed by Chiang Mai at 17 and Nakhon Ratchasima at 13.

Nearly two million vehicles were stopped at checkpoints around the country and 33,719 people were charged. Most were motorists unable to present their driver's licence, followed by riders not wearing safety helmets and drivers not wearing seatbelts.

With summer thunderstorms and gusty winds forecast for the North and Northeast over the next few days, Theera urged motorists to exercise more caution.

The minister urged people to call 1356 or 1784 if they wanted to know about traffic congestion on routes to the North and Northeast, accident reports or other travel information.

To reduce traffic problems, the Disaster Prevention and Mitigation Department also asked trucks not to drive on Bangkok's outbound lanes from Wednesday to Sunday (April 11 to 15).

Thick traffic has been reported on the Mitraparp Highway from Saraburi to Nakhon Ratchasima town since Wednesday night, and bus terminals at Korat (Nakhon Ratchasima) were crowded with travellers.

The slow traffic appears to have caused some drivers to lose concentration.

A pick-up loaded with factory workers on their way to Si Sa Ket lost control and crashed into a roadside tree yesterday at 7am in Nakhon Ratchasima's Nong Boon Mak district. Four people were killed and nine others were seriously injured. Police suspected the driver, Suwit Phadsungnoen, 24, fell asleep at the wheel.

Meanwhile, Public Health Minister Dr Mongkol na Songkhla yesterday inspected central hospitals in Nakhon Ratchasima and Saraburi to check if they were prepared for possible road casualties around the clock.

Mongkol said that on Wednesday alone, emergency medical services (EMS) units nation-wide were dispatched 1,267 times, about 53 times an hour - a 37-per-cent jump over the same period last year.

About 534 - or 40 per cent - of the calls were for road accidents.

Public Health permanent secretary Prat Boonyawongvirot noted that 571 prank calls were made to the Narenthorn EMS Centre's hotline 1669.

The Disaster Prevention and Mitigation Department also warned people of eight dangerous routes, which had the most accidents over the past three years. They were:

l a downhill mountain stretch on the Mitraprap Highway (KM136-138) in Saraburi's Muak Lek district;

l a curved section on Paholyothin Highway (KM76-77) in Ayutthaya's Wang Noi district,

l KM66-67 on the Asia Highway in Ayutthaya's Bang Pa-in district;

l a busy stretch on the Petchkasem Highway (KM152-153) in Phetchaburi's Muang district.

Others areas to watch are three sections on Sukhumvit Highway number three (KM129-130, 145-146, and 4-7 in Chon Buri) and KM6-7 on Sukhumvit Highway number 344.

Meanwhile, Ladda Tangsupachai, director of the Culture Watch Centre, warned female revellers playing with water over Songkran not to wear too revealing clothes and to watch out for sexual harassment.

She also said that the Culture offices nation-wide were instructed to watch for - and immediately stop - inappropriate shows, especially "Coyote girls" and other sexually provocative or obscene dancers.