This week's car accident on an elevated expressway which saw an elderly woman thrown to her death has prompted authorities to look at clamping down on drivers who treat the hard shoulder as an extra lane during rush hours.
"The hard shoulder has never been a regular traffic lane," deputy city police chief Chiraphat Phumichit said on Wednesday, vowing to take legal action against drivers who flout the law and use them as a convenience.
This long, narrow strip is only for broken down vehicles or for ambulances rushing patients to hospital, Pol Maj Gen Chiraphat said.
The move to prevent motorists from using expressway hard shoulders will be a joint effort undertaken by the Metropolitan Police Bureau, other state agencies such as the Expressway and Rapid Transit Authority of Thailand (Exat) as well as the Accident Prevention Network.
All the organisations discussed the matter in an urgent meeting on Tuesday, the day after the tragedy.
The tragedy occurred during morning rush hours on Monday when a Toyota Fortuner trying to beat traffic ran into a broken down KIA van parked on the hard shoulder of the Chalongrat Expressway near the Sukhumvit 50 exit.
The crash propelled 68-year-old Thanyapat Wipanpong over the barrier and fall to her death on a road below.
Three other people, a policeman, the Toyota's driver and a pregnant woman in the van were injured.
These types of accident have become quite frequent Pol Maj Gen Chiraphat said.
Stiffer punishments against violators will be one measure to stop motorists, the deputy city police said, adding that those caught would be fined up to 1,000 baht.
Exat also plans to create uneven surfaces along hard shoulders, that will make them uncomfortable to travel along, its deputy governor Dumkerng Pankam said.
He said various campaigns to persuade drivers not to use hard shoulders have all proved ineffective.
One reason is people wrongly believe they are "allowed" to drive on them and think they are an easy way to beat traffic congestion during rush hours, said a representative from the Accident Prevention Network.