Beltala: The transport department has seized at least a dozen school buses that ferry students of some of Calcutta's top institutions for avoiding the mandatory test of roadworthiness or operating without valid permits.

Around 30 pool cars have also been towed away for various offences, including plying without fitness certificates, road permits and even valid tax tokens.

The buses and pool cars seized so far ferry students of South Point, Gokhale Memorial Girls' School, Don Bosco School Park Circus, DPS Ruby Park and St John's Diocesan Girls' Higher Secondary School, among others.

"This shows how schoolchildren are put at risk every day," said a senior officer of the public vehicles department (PVD). "Some of the schools have told us that private agencies run their buses. But their culpability cannot be denied."

School buses and pool cars are often accused of violating safety norms and no complying with various transport regulations. But they somehow manage to evade prosecution.

Motor vehicle inspectors and police argue that it is not practical to intercept school buses and carry out compliance checks when children are being ferried. This leniency has allowed ramshackle buses plying on resoled tyres and rickety cars to be used as school transport.

The last such drive against unsafe and unauthorised school transport was in July 2016.

In the second half of July, officers of the enforcement wing of the PVD split into groups to stop and check buses and pool cars after they had dropped off children at various institutions.

The outcome of the drive was an eye-opener. Some buses had a fresh coat of yellow-and-blue paint but failed the scrutiny of documents, including tax tokens, permits, registration and fitness certificates.

A school bus (WB37 D 0805) ferrying students of a reputable school hadn't renewed its fitness certificate after it lapsed on April 28. Another bus (WB 25B 3994) was found plying with a fitness certificate that lapsed on August 4 last year.

Most schools blamed private operators for the violations, saying that they didn't have buses of their own.

The practice across institutions is to hire multiple operators to ferry their students.

School managements usually don't bother checking if these operators are complying with transport regulations, including up-to-date documentation, unless there is a specific complaint regarding quality of service.

"We have about seven to eight buses and around 12 pool cars ferrying our students," said an official at Gokhale Memorial Girls' School. "The school has no contractual agreement with any of these transport operators. But we do try and ensure that there is no reason for complaint. As far as documentation is concerned, we leave that to the operators."

Most of the other schools that Metro spoke to said they needed to check with the operators and transport authorities before coming out with a formal response.