The retreaded, worn-out tyre (top) of the pool car that overturned on the EM Bypass on Monday; Debaditya Chowdhury at home after the mishap. Pictures by Sanjoy Chattopadhyaya

Ten schoolchildren and a teacher were trapped upside down in an illegal pool car for a few minutes on Monday after the speeding vehicle overturned on the EM Bypass because of a worn-out tyre.

Debaditya Chowdhury, a Class VII student of St Xavier’s Collegiate School, was busy brushing up on his physics for an exam scheduled to start at 9am when he heard the tyre bursting and the Tata Sumo ramming into the divider. “The next thing I knew, I was lying on my back with feet in the air. It was scary till we were pulled out to safety,” the boy from Kaikhali told Metro.

Debaditya and his co-passengers, all from the same school, suffered only cuts and bruises but the experience left them and their parents traumatised.

The Pool Car Owners’ Welfare Association said the vehicle involved in the accident (WB26C 4418) was illegally ferrying children to and from school. “It is not registered with any of the pool car associations of the city,” said Arup Roy, the president of the welfare association.

The car was also carrying passengers in excess of its seating capacity. A Tata Sumo can seat only nine persons, including the driver.

Aparna Sikdar, the Bengali teacher who was in the vehicle, said the pool car picked up the last passenger at Salt Lake and was speeding down the Bypass when the accident occurred between Chingrihata and the Parama rotary.

“School was scheduled to start at 9am on Monday, which is half-an-hour earlier than the normal time, because of exams. We were still on the Bypass at 8.40am and our driver was trying to overtake a Calcutta Tram Corporation bus that was blocking the way when the tyre burst.”

Hemmed in by the divider and the bus, the pool car driver lost control when the resoled rear left tyre burst. The car hit the divider at high speed and rebounded before landing on its roof.

Mukul Mahato, 15, said the only thing he remembered was being flung off his seat. “I was in a daze long after the accident. I didn’t know what hit me,” he said.

The driver of the Tata Sumo wasn’t arrested because no parent or guardian filed a complaint against him. “We have only registered a case of negligent driving. The guardians who spoke to us said the accident was caused by the flat tyre and that the driver was not at fault,” an officer at the Parama Investigation Centre said.

Pool cars in Calcutta have been involved in several accidents over the past couple of years. There have been at least three this year, including the one on Monday.

A teenaged girl needed 57 stitches on the face and another required 22 after a pool car carrying them and two other students hit a pavement in the rain on January 30. The students were returning home from Assembly of God Church School, on Park Street.

Another unlicensed pool car with an illegally fitted LPG cylinder at the back had caught fire on July 10, leaving eight students gasping for breath till they were rescued.

The Supreme Court’s guidelines for pool cars include seat belts for all passengers, a first-aid compartment and an attendant in each vehicle. Pool car associations are supposed to ensure that drivers are trained well and the vehicles, especially tyres, are in good shape.