Speed breakers not built to specifications kill traffic and cars in Calcutta as much as speed kills people on roads where rash driving is rampant.
Several city roads have so many speed breakers in succession or bumps where none is required that they pose a hazard to traffic rather than curtail car speed, which in some thoroughfares now matches that of a healthy Calcuttan on a brisk morning walk.
Too many bumps along a stretch might lead to congestion and give pedestrians less time to cross the road than they would get with a properly planned traffic regulation system, said Bhargav Maitra, a professor at IIT Kharagpur who has published several papers on traffic management.
Speed breakers often come up in various parts of the city at the behest of local residents without official sanction and/or in violation of the guidelines of the Indian Roads Congress, the apex technical association of traffic and road engineers.
A speed breaker should be built only where it is necessary. It should not cause any damage to a vehicle or excessive discomfort to the driver and passengers, said R.V. Patil, the assistant director (technical) of the roads congress.
The associations manual states that speed breakers must be 0.1 metre in height and 3.7 metres wide on roads where traffic moves at an average speed of 25kmph.
Metro found speed bumps in parts of Mukundapur, Broad Street, Tollygunge and Taltala to be much higher than the specified height. Broad Street has eight bumps along its 800 metres while the kilometre-long Rifle Range Road has nine.
The average speed of cars on a few of these stretches is less that that specified for a speed breaker to be sanctioned.
The Telegraph had highlighted on Wednesday how the average speed of a vehicle on some city routes had dropped to 7kmph because of bad roads and faulty traffic management, including signals too many.
In Calcutta, speed breakers save lives on several thoroughfares but also damage vehicles because of the unscientific way in which they have been created.
There are twin bumps on the road near Tallah tank which the undercarriage of my car grazes almost every day, complained Bengal cricketer Jayojit Basu, who lives in the area and drives a Honda Brio.
Sudeshna Ghosh, a resident of Mukundapur who drives a Ford Ikon, has had to take her car to the garage after similar damage inflicted by extra-high road bumps.
In central Calcutta, those who commute through Ripon Street and Doctor Lane would be familiar with such bottom-scraping bumps.
Garage owners say speed breakers damage a cars bumper, radiator, chamber and even the engine. We receive three cars a month on an average that have been damaged by road bumps, said Manash Dalapati of Raja Automobiles, on Prince Anwar Shah Road. The cost of repair can go up to Rs 5,000-6,000.
Most speed breakers are apparently knee-jerk reactions to accidents. The ones that have come up on APC Road recently in sets of two and three are among those forced on traffic. Thoroughfares are not supposed to have speed bumps but APC Road has five.
We do not construct speed breakers on our own. Members of local clubs or residents force our contractors to build them during road repairs, said CMC chief engineer (civil) P.K. Dhua.
The rule book recommends painting bumps in alternate black and white or black and yellow bands but the city has few of them. A warning sign at least 40 metres ahead of a bump is a must.
Here, signs are invariably put up right next to the speed breakers. They are not warning you, but merely informing you that you are about to meet with an accident, said IIT professor Maitra.