The driver of the van involved in a horrific crash in Chon Buri which left 25 dead on Monday was likely to have dozed off behind the wheel as he had made five round trips within 31 hours, according to officials.
The van, which was heading from Chanthaburi to Bangkok, a distance of 250km, when it swerved out of its lane and crashed into a pickup truck travelling in the opposite direction on a highway in Chon Buri's Ban Bung district.
A fire broke out in the van following the crash, which subsequently killed 14 out of 15 people on board, including the driver. The collision also killed 11 of the 12 people in the pickup.
Ponsak Thaijeam-aree, chief of the Chanthaburi Land Transport Office, said the van driver, Sumon Eiamsombat, 64, started work at 4am on Jan 1, when he left Chanthaburi for Bangkok. He began his second trip at 11.30am when he left the capital for the province. He later departed from Chanthaburi to Bangkok at 6pm.
On Jan 2, he started working at 5am, when he left Bangkok for Chanthaburi, and set off to return from the province at 11.30am.
"The driver should have had more rest and this was likely to be the cause of the crash," Mr Ponsak said.
The van did not check in at the Chanthaburi terminal as required and Transport Co was contacted for an explanation, he said.
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Meanwhile, Chon Buri authorities organised a teleconference with Transport Minister Arkhom Termpittayapaisith to discuss the incident.
Chon Buri governor Pakarathon Tienchai said officials who inspected the scene reported there were traces of the brakes being used at the spot where the van was seen losing control and crossing a ditch dividing the road before colliding with the pickup.
"The van driver was believed to have fallen asleep behind the wheel as he was 64 years old," the governor said.
When he regained consciousness, he tried to brake while the vehicle was moving at a high speed, causing the vehicle to veer off the lane and hit the pickup in the opposite lane, he said.
However, Mr Pakarathon said this was only the most likely cause, based on initial investigation at the accident site and conversations with some witnesses. A more thorough investigation is still needed to determine and prove the cause of the accident, he said.
Mr Arkhom said the labour law stipulates drivers for transport vehicles must not work more than eight consecutive hours and in this case, the investigation must look into how long the van driver had been working.
The incident may have been caused by driver fatigue and the speed at which he was driving, he said. The van passed a check in September last year and no problem was found with its gas cylinder.
It is probable that the fire was triggered by the fuel system, but further investigation is needed, the minister said.
"In foreign countries, vans are not designed to transport passengers, but to carry stuff," Mr Arkhom said. "When we use this vehicle with a dual fuel system for this purpose, the focus must be on safety."
Van drivers must also stick to the Department of Land Transport's (DLT) regulations, which stipulate that drivers must rest for one hour before each four-hour drive.
By 2019, efforts will be made to reduce the number of inter-provincial vans and increase the number of larger vehicles to ensure safety, according to the minister. Drivers must also undergo training every six months to remind them of the traffic laws and boost their awareness.
Meanwhile, a conductor at the queue for the vans, run by Ploy Yok Partnership Limited, insisted the driver was well-rested before driving.
Patarapong Sua-nak said Sumon arrived at the queue at 10am and had had enough rest.
The company checked if the driver was feeling okay before allowing him to drive the round trip at 11am from Chanthaburi to Bangkok, he said.
Siwakon Buapong, chief of the Disaster Prevention and Mitigation Provincial Office in Chon Buri, said the driver should have had more rest after the five-hour drive from Bangkok to Chanthaburi.
"Most van drivers' earnings are based on round trips as well as a percentage from passenger fares. This gives drivers an incentive to drive fast in order to make more round trips, particularly during the New Year period," said Mr Siwakon said, adding more safety equipment should have been installed in the vehicle.
DLT director-general Sanit Promwong said Ploy Yok has insurance coverage and 700,000 baht will be paid to the families of each victim.
The Global Positioning System (GPS) has not yet been installed in the vehicle. All the vans must be installed with the system by this year, based on the DLT's announcement, he said.
Mr Sanit said the DLT wrote to Transport Co demanding it revoke Ploy Yok's operating licence.
The company, which has 18 passenger vans in service, will be monitored closely by provincial officials, he said.