Esplanade: Almost half the fleet of 30 buses on route 007 between Kolkata station and Garia did not ply on Thursday.

On route 85, Kanchrapara to Barrackpore, seven out of 14 buses remained off the roads.

Chetla to Howrah, route 17, had 30 out of 60 buses missing.

Buses across several other routes were grounded on Thursday as private operators scrambled to calculate the returns that a Re 1 fare hike for each 4km slab would fetch. The general view was that it would do little to ease their pain.

The transport department is supposed to notify the fare hike in a day or two. But even before the new fare chart takes effect, most private bus and minibus operators are ready to press for a bigger increase.

Bus operators had proposed that the 4km slab be altered to 3km. They wanted the minimum fare to be Rs 9 against the existing Rs 6. The price of fuel, the operators had argued, had gone up by nearly Rs 12 and other costs, including insurance, licensing, tyres and manpower, had increased by 12 to 15 per cent since 2014, when fares were last revised.

"Would the government please come out with the model that it used to arrive at the figure of Re 1? We would like to know what convinced the planners that a Re 1 hike would suffice," Tapan Bandyopadhyay of the Joint Council of Bus Syndicates told Metro. "Successive state governments in Bengal have increased fares without using any scientific model," he said.

According to him, the association agreed not to go on strike only because chief minister Mamata Banerjee had made a request to accept the Re 1 hike.

Bus operators had been called by Mamata to Nabanna on Wednesday and asked to cancel the bus strike that was to start on Thursday.

A partial strike did take place, albeit unofficially.

The fleet of private buses in and around Calcutta has dwindled from close to 9,400 five years ago to around 8,500, with several operators citing low returns on investment.

The arithmetic they show is that if a bus travels around 24km every day for 25 days, it will end up ferrying around 600 passengers a day on an average. In that case, a bus owner will earn between Rs 7,000 and Rs 8,000 a day.

"Out of this, cost of fuel is around Rs 3,000. A driver gets 12 per cent of the earnings, which is Rs 720 a day. Ditto the conductors. Around Rs 300 goes into spot fines. If you consider Rs 25,800 to be the EMI for a bus loan, an owner is left with almost nothing at the end of a month," said a private bus owner on route 230.

Officers at the transport department said they had calculated the fare structure by taking into account several factors including inflation and diesel price.