At least 25 Cognizant Technology Solutions employees were injured on Tuesday when an AC bus ferrying them collided with a lorry on Basanti highway.

The driver of the bus on the Airport-Calcutta Leather Complex (Bantala) route, according to some of the employees, jumped flanks while overtaking a car on the cramped highway, about 12km from Science City. The highway's expansion has hit a roadblock because of illegal encroachments and land problems in some areas.

Six people were admitted to two private hospitals on EM Bypass and three are in a critical care unit. The rest suffered minor injuries and were discharged after being given first-aid.

The injured driver, Kamal Haldar, was admitted to Rabindranath Tagore International Institute of Cardiac Sciences with leg, stomach and rib injuries.

Haldar lives in Subhashgram in South 24-Parganas. His family members have been alerted.

Police said the accident occurred around 9.45am when the AC bus was ferrying close to 45 Cognizant employees to their office inside the Bantala Leather Complex on Basanti highway. At least 10 people have died in road accidents on the highway in the past 13 months.

The front right side of the bus was smashed and some of the seats came off under the impact of the crash.

According to employees who were in the bus, the driver was speeding and trying to overtake other vehicles throughout the journey by jumping flanks. The bus hit the truck at Katatala.

Subhanga Chatterjee, 31, Tapan Manna, 34, and Mini Thakur, 34, are in the critical care unit of Ruby General Hospital.

'Chatterjee fractured his spine, jaw and nose. There are multiple cuts on his face as well,' an official of the hospital said. Manna's right leg has multiple fractures. His forehead is injured, too. Thakur's pelvic bone is fractured. Chatterjee and Manna were likely to undergo surgeries on Wednesday, the official said.

Three other employees were operated upon at Apollo Gleneagles Hospitals for fractures and cuts. 'All of them are stable,' a hospital official said.

The 16-km stretch between Science City and the leather complex does not have any road divider to prevent further narrowing down of the carriageway.

Anindya Bhaumik, who fractured his shoulder, said: 'Throughout the journey, the driver kept speeding and overtaking other vehicles by jumping flanks. We were about 2km from our office when he tried to overtake a car and moved to the wrong lane. But this time there was a sand-laden truck coming from the opposite side.'

Another employee said the injuries would have been more severe had the truck driver not slammed the brakes.

'The bus was moving so fast that the driver could not even apply the brakes. The truck driver slammed the brakes but by then the bus had hit it,' Subhasish Bose said. Bose's right leg was injured but an X-ray did not reveal any fracture.

The West Bengal Surface Transport Corporation bus operates between the airport and the leather complex. Almost all passengers beyond Science City are usually Cognizant employees.

Several Cognizant employees travelling on the same route said bus drivers often speed despite their opposition. 'Every other day we see an accident on this stretch involving buses that either speed or jump flanks to overtake. We often tell bus drivers not to speed but they ignore our requests,' Sambuddha Bhaumik said. He was at Apollo Gleneagles Hospitals to help his injured colleagues.

The Cognizant office has come up in a 130-acre special economic zone, carved out of the 1,200-acre leather complex in Bantala. And the 105km Basanti highway is the best route to reach there from the city.

Vehicular traffic on this road has increased because of a rise in the number of tourists visiting the Sunderbans and several offices that have come up along the highway.

But the government has failed to expand the highway because of its hands-off land acquisition policy and encroachments on either side of the highway. 'People have set up illegal shops and eateries on either side of the highway. In a few place we have not been able to acquire land to expand the highway,' said a PWD official.

According to officers of Calcutta Leather Complex police station, people tend to speed on Basanti highway because of its good condition and that leads to frequent accidents.

In March last year, a techie and his driver were killed when their speeding car skidded off the highway and fell into a canal while negotiating a sharp turn near Koila depot.

In the same month, Mohammed Amin, the husband of Calcutta Municipal Corporation's deputy mayor, died at the same spot in a two-wheeler accident.

In December 2013, three people died in two accidents near Koila depot.