A campaign to reduce traffic on Sathorn Road has hit a speedbump with drivers refusing to change lanes.
The Transport Ministry launched the so-called "Sathorn model" in November with ambitions to expand it to other congested areas in Bangkok.
Bangkok Christian College on Sathorn was targeted at launch as it is a source of traffic jams during mornings and afternoons when parents drop-off and pick up their children.
The ministry has worked with department stores and condominiums near the school to provide short-term parking with students shuttled to and from the school in vehicles provided by campaigners. Parents who want to leave the cars there all day pay a monthly 2,000-baht fee.
The plan was curb traffic queues in front of the school, but seven months into the campaign, only 22 parents had signed up for the project, Pongchai Kasemthaweesak, deputy permanent secretary for transport, said on Tuesday. That puts the campaign far behind its goal of attracting 300 drivers by August.
Campaigners haven't thrown in the towel yet, however.
"We have to find ways to solve this problem and run the campaign until the end. Then we will make an evaluation and decide whether it should continue or not," said Mr Pongchai.
Despite the lacklustre progress, Saksith Chalermpong, an academic at the engineering faculty of Chulalongkorn University, said it was premature to conclude that the Sathorn model was a failure and was adamant that drivers would join in.
The main challenge is changing the behaviour of parents to stop them driving to school, said Mr Saksith, who is in charge of parking for the project. The monthly parking fee also is too high, he added.
Mr Saksith said he was finding ways to make it more popular by convincing parking providers to reduce fees. Organisers also plan to add incentives, such as department-store discount coupons and discounted BTS tickets for parents.
Sathorn is one of the most congested roads in the capital. Almost 68,000 vehicles ply the road every day, 65% of which come across the Chao Phraya River on the Taksin Bridge from Thon Buri. The average speed on Sathorn is 20 kilometres per hour.