The Bypass site where a bus toppled over on Wednesday

Motorists in Calcutta tend to treat the amber traffic signal as green often out of callousness and sometimes out of ignorance, both of which are mostly ignored by police until a tragedy occurs.

A government-owned bus had rushed past an amber light at the busy Science City crossing on Wednesday evening and toppled over on its side after colliding with a private vehicle that had just turned right towards Park Circus.

The accident, which claimed a life, not only highlighted the face of irresponsible driving in the city but also the general lack of regard for traffic rules and safety.

In Calcutta, thousands of motorists misread the amber for green every day and put their own lives and that of others at risk, police officers said.

According to statistics available with the traffic police department, private cars accounted for 85,350 of the 2.5 lakh cases registered in 2013 for jumping traffic signals. The number of buses “prosecuted” for jumping signals was 60,133.

“Ideally, the moment you see the light turn amber, you should stop, unless you have already crossed the stop line. But the natural tendency is to press the accelerator instead of the brakes. Most of the vehicles that continue to move even after the light turns amber at busy crossings cannot make it to the safe zone before it turns red. Hence, they become culpable for prosecution,” said a senior officer of the traffic department.

Any vehicle that has yet to cross the stop line and starts accelerating after seeing the light turn amber gets only a few seconds before the signal turns red. “If your vehicle is crossing the intersection when the signal is red, it is an offence and attracts a penalty,” the officer said.

These are basic rules that the motor vehicles department recommends should be drilled into anyone learning to drive. But they are often forgotten once the driver hits the road.

Driving instructors allegedly often skip a part of the basic training schedule, starting with how to read traffic signals, and people aspiring for a driving licence without proper training manage to get through by paying a few hundred rupees extra.

“It is no secret that driving licences can be bought. We cannot expect responsible driving from those who do not even sit for the driving test but have a licence to flaunt,” a police officer said.

Sources said the fine of not more than Rs 100 that a motorist is charged for jumping a traffic signal isn’t enough to turn an otherwise law-breaking driver into a law-abiding one. Worse, such violations pose a threat to life and limb.

A veteran officer in Calcutta police’s traffic department said: “Signals at the big crossovers are timed in a way that if the east-west light turns amber, the north-south corridor automatically opens with a green light. Hence, if vehicles plying through the east-west corridor don’t stop at the amber light, a collision with traffic in the north-south corridor is a strong possibility.”

The 22-year-old youth who died when the bus toppled over on the Bypass on Wednesday evening hadn’t been identified until late on Thursday.