Test to find out north roads' vulnerability

Kinsuk BasuTT, Calcutta, Aug. 17: A committee set up by the state government has decided to test some of the materials that were collected from ri, verbeds to construct highways and roads in north Bengal to find out the reasons behind their fast deterioration and suggest ways to make them sturdier.

The first-of-its-kind committee, which has as members experts from IIT Kharagpur, Jalpaiguri Engineering College and engineering consultancy company Rites and engineers of the public works department, has decided to send riverbed shingles used to build roads to two government labs. Tests will be done to find out why roads in north Bengal suffered repeated damage and how the roadbeds were laid before they were covered with layers of asphalt.

"Some of the roads, including NH31D, NH31C and a stretch of NH34, are in a bad shape. The state government is also building a potion of the Asian Highway (that will connect Bangladesh and Bhutan via north Bengal). We want to find out how roadbeds can be made sturdier so that the roads don't develop potholes," said a PWD engineer who is a member of the committee.

Nabanna sources said that during one of her recent visits to north Bengal, chief minister Mamata Banerjee was "furious" after learning that several roads in the region were either caving in or developing potholes despite the government spending crores on their repair and maintenance. After returning to Calcutta, she set up the committee primarily to find out ways to prevent the formation of craters.

The foundations of most highways and other roads in north Bengal are built using shingles that are collected from the beds of the rivers criss-crossing the region. The shingles are mixed with sand in proportions stipulated in a central government manual.

Sources in the PWD, which is responsible for the maintenance of several roads in north Bengal, said the riverbed shingles were used because of the state government's insistence on "locally available materials" to build roads.

The committee will examine whether the riverbed shingles can bear loads. Roads in south Bengal mostly use bricks, stones and gravel and are sturdier, sources said.

The samples will be sent for tests to the labs of Jalpaiguri Engineering College and the Road and Building Research Institute in Poilan, on the southern fringes of Calcutta.

The lab tests will look into various aspects of the shingles, including their physical properties, their ability to withstand load on a daily basis, how prone they are to subsidence, their binding capacity and their compatibility with the soil of north Bengal, another committee member said. "Once the results reach us, we will discuss the next step."

The PWD sources said there was another reason why the committee has been formed. They said an alternative to shingles had to be found because of a National Green Tribunal ban on the digging of riverbeds for sand-mining and lifting materials used to lay roads. The ban was issued in March.

Engineers said that following the ban, the only alternative was to get gravel and shingles from Pakur in adjoining Jharkhand.

"But that will be costly. The committee will try to come up with an alternative so that the cost of constructing roads is brought down significantly," a PWD engineer said.