Rail-grinding to ensure quieter train movement along Kolkata’s East-West Metro corridor

KOLKATA: When trains operate on the East-West Metro line, they will be quieter than the existing north-south Metro. Kolkata’s Metro line 2 has just undergone rail-grinding along the 9km stretch between Sector V and Sealdah so that trains generate less sound when they start plying between Sector V and Salt Lake stadium next month. Grinding reduces noise, improves ride comfort and enhances longevity of the tracks and rolling stock.

“To reduce the noise generated when trains ply on the viaduct, and later in the underground tunnel, the tracks have been smoothed through the rail-grinding process,” said an official.

Kolkata Metro Rail Corporation (KMRC), the implementing agency of the Rs 8,575-crore project, imported the rail-grinding equipment from Namma Metro, also known as Bengaluru Metro, and used them to grind the tracks in May. A rail-grinding machine evens out the tracks by removing irregularities or corrugation on the surface and ensures smoother track-rake interaction. An engineer involved in the project said the sound level had reduced to less than 70 decibels after rail-grinding.

Some Salt Lake residents will have an extra privilege since KMRC will install sound barriers at DL Block, around City Centre and near Sector V, where buildings are within 30m of the tracks. The micro-perforated stainless steel barriers can reduce noise level by at least 20 decibels. But this would be an experiment for now. The more permanent measure against sound pollution — rail-grinding —will be extended beyond Sealdah once track-laying is completed. The last leg of tunnelling is on from Esplanade to Sealdah at present.

“During a recent inspection, we found that the noise caused by train movement was less than 70 decibels, which is well within the permissible range mentioned in the Metro Railway manual,” said an official.

A noise study carried out in 2010, before the construction of the viaduct, had taken the notional value of noise generation. “Once the trial runs started, we could ascertain the exact level of noise generated from rake movement. It was quite high. So we decided on rail-grinding,” the engineer said.

In the north-south line, the sound level of trains running on the rails is 85 decibels-90 decibels. At times, the noise is so deafening that it is difficult to hear announcements, especially during peak hours when the trains are packed.