Transport authorities will curb the number of tuk-tuks on the roads as a recent increase is affecting quality controls on the iconic three-wheel passenger vehicles.
Tuk-tuks need "birth control," said Land Transport Department director-general, Sanit Phromsathit, after learning their numbers in Bangkok have risen to more than 9,000.
Mr Sanit said the department considered this as excessive, and made it hard to supervise their operations.
Officials will halt new registrations of tuk-tuks except those under the tuk-tuk uea athon scheme run by the Transport Ministry to promote tuk-tuk driving as a career as well as the use of clean energy.
The public makes fewer complaints about tuk-tuk services than metred-taxis, but some passengers have complained about safety issues prompting officials to cut back on the number of the three-wheelers so inspection procedures can be more efficient.
Most tuk-tuk passengers are worried about careless, high-speed driving which puts them at risk of being thrown out of the vehicles, Mr Sanit said.
Last year authorities brought in a new regulation demanding tuk-tuks be fitted with a steel structure on the right side of the car to prevent passengers falling out.
The ministry has also set a standard length and width of the vehicles and prohibited drivers from adapting them. Modifications can cause the vehicles to tip over.
These issues call for a need to "keep tuk-tuks in order and make sure passengers can travel safely", Mr Sanit said, adding the goals would be hard to attain if there is no ceiling on the number of the vehicles operating.
Registrations will only be accepted for three-wheelers under the tuk-tuk uea athon scheme, so long as the vehicles are run on compressed natural gas and drivers are residents in Bangkok, Nakhon Pathom, Nonthaburi, Pathum Thani, Samut Sakhon and Samut Prakan.
Mr Sanit said 2,100 of the 2,500 tuk-tuk drivers under the project have their vehicles registered.
The department has no plans to set fare rates. Mr Sanit said that fares will still be need to be negotiated between drivers and passengers.