The state government has decided that the speed limit on Calcutta’s roads will vary between 25 and 50km per hour for all vehicles.

A notification issued by the transport department on Friday — it came into “immediate effect” — states that the speed limit for vehicles in school zones will be 25kmph.

The limit will be 50kmph in areas where “vulnerable road users are largely protected or segregated from motorised traffic” and where there is no “on-street parking”.

To begin with, the speed restrictions will be implemented mostly on major roads after putting up the necessary display boards, said a senior officer of Kolkata Police.

“We have decided to install additional speed cameras to enforce lane discipline and the speed limits on many roads, including EM Bypass, AJC Bose Road, APC Road and the Bypass-Prince Anwar Shah Road connector,” the officer said.

The notification specifies four speed limits for vehicles on urban roads.

In areas where schools are located, the speed limit will be 25kmph. The speed limit will be 30kmph for vehicles moving through roads where pedestrians spill over without much hindrance and on roads with a mix of slow-moving and speeding vehicles, such as MG Road.

The speed limit on roads not categorised under the 25, 30 and 50kmph categories is 40kmph.

The notification, signed by Manoj Pant, Bengal’s chief secretary and chairman of the state’s road safety council, states that the speed limits have been decided to “effectively reduce road accidents”, following a decision by the council.

Urban and rural areas have different speed limits, the notification says.

Senior transport department officials said thespeed limits were arrived at after considering inputsprovided by the police and various departments such as urban development, public works, health and school education.

IIT Kharagpur collated the inputs, observed the traffic pattern in urban and rural areas of Bengal and analysed the nature of road accidents before coming up with a set of recommendations, based on which the notification was finalised.

“We will soon prepare signage and boards specifying speed limits on roads. The police and other agencies will be part of the exercise,” said a senior transport department official.

The existing speed limit for cars on some city roads, including the AJC Bose Road flyover, EM Bypass, Bypass-Park Circus connector, Bypass-Rashbehari connector and the Parama flyover is 60kmph.

The current speed limit for two-wheelers on flyovers has been 40kmph since the time the government decided there would be no time bar for them to use flyovers.

On EM Bypass, the existing speed limits for buses and two-wheelers are 40kmph and 50kmph, respectively.

“Once the notification comes into effect, the speed limit for any category of vehicles will not exceed 50kmph,” a transport department official said.

“The 50kmph limit is for roads such as EM Bypass where there is little or no interference to traffic because of unmanned intersections,” the official said.

Senior members of IIT Kharagpur’s Reach and Analysis team, which studies accident patterns and types of vehicular flow, said this was the first attempt to fix speed limits scientifically across Bengal’s rural and urban roads.

“An analysis of the accident data revealed that speeding by vehicles remains the main reason for accidents. Around 70 per cent of vulnerable road users are pedestrians and bicyclists,” saidBhargab Maitra, a professor in the IIT’s civil engineering department.

Maitra’s specialisation includes design and evaluation of pavements, public transportation, traffic management and safety.

“We have found that if a vehicle hits a pedestrianat 30kmph, the chance ofdeath is just around 10 per cent. A thoroughfare with a smooth surface may begood for speeding. But it iscrucial to determine whether a vehicle can be allowed to move through it at a high speed factoring in the types of vehicles using the road,” Maitra said.

Senior state government officials said a teamwould review the speed restrictions and bring about necessary changes if required after observing the flow of traffic on urban and rural roads.