Passengers sitting in the bed of a pickup truck are eight times more likely to die in a road accident than those inside the vehicle with their seatbelts fastened, according to a US study cited by the Thailand Accident Research Centre (Tarc).
The study was disclosed at a seminar held by road safety promotion groups following an accident in Samut Prakan last week in which a pickup truck overturned, killing 17 technical college students who were sitting in the rear.
Another study mentioned by the centre found the risk of a 1.5-tonne truck overturning in a road accident is 12%.
However, the risk increases to 28% if 10 people weighing 60kg each sit in the rear section. And it quadruples if the 10 passengers are standing, according to the study.
Other factors were also identified in the Samut Prakan accident including driving under the influence, speeding, reckless driving and overloading the rear bed.
A survey carried out by the centre found that about 50% of people who usually travel in the rear bed of a pickup are aware of the dangers they face.
However, they insisted they had little choice in travelling in that manner, according to Tarc.
Only one-third of the 200 passengers surveyed believed that travelling in the rear bed of a pickup truck posed no extra risk of injury or death.
In most cases, passengers die as a result of falling from the truck bed when the vehicle makes a sudden change of direction or overturns, said Thanaphong Chinwong, manager of the Road Safety Policy Foundation's (RSPF) academic centre.
Passenger mortality is usually caused by landing hard on the road surface or the ground or if they hit power poles or a hard wall, he said.
One measure that may help prevent deaths and injuries associated with a pickup truck overturning is to raise public awareness, he said.
Dr Thanaphong said the awareness could be ramped up through public campaigns that educate people about the importance of obeying the rules of the road; in particular, the law which limits the number of passengers allowed to travel in a truck bed to six people, provided the vehicle is fitted with safely-secured solid metal bars in the back.
Also, the speed limit of 80km per hour on main roads must be observed, said Dr Thanaphong.
An attempt to introduce a ban on passengers travelling in the back of pickup trucks two years ago met with strong resistance from the public, said Pol Lt Col Phacha Thapanadul, a traffic police inspector with the Traffic Police Division.
The truck in the Samut Prakan accident was one of about 8 million vehicles that do not have an insurance policy which covers road accidents.
Such a policy would likely have seen the families of the deceased receive up to 300,000 baht each in initial compensation, according to an insurance firm estimate.