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The nightmare before that dream drive to Shimla

Conceived to ease traffic congestion on National Highway-22, four-laning of the 39-km Parwanoo-Solan stretch has become a nightmare for motorists with landslides plaguing the highway this monsoon.

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Ambika Sharma in Solan

Conceived to ease traffic congestion on National Highway-22, four-laning of the 39-km Parwanoo-Solan stretch has become a nightmare for motorists with landslides plaguing the highway this monsoon.

Accidents have become a routine with falling boulders damaging vehicles passing by. Last year, a Nangal resident was killed after his vehicle was trapped under the falling debris at Samlech. A youth was grievously injured near Timber Trail Resorts due to falling boulders. Yet another family had a narrow escape when huge boulders and debris fell on their vehicles at Patta Ka Mor recently. With four-laning making the mountains instable, these are not isolated incidents. Motorists dread driving during the night when the risk of accidents is the maximum.

The last month has been dreadful. Rains triggered landslides at several places posing a threat to several houses atop hills in Dharampur and Solan. Gaping cracks are a common sight in these houses.

But why are rains wreaking havoc in the mountains? Why are the hills sliding, eroding them at an alarming pace, especially between Dharampur and Kumarhatti and near Chakki ka Mor. Was it safe to drill through these fragile shale and sedimentary hills?

One reason could be the low height of the breast walls erected to hold the hills. These are barely 1.5m to 3m high and have proved ineffective in preventing landslides. Realising the need to construct higher walls, the company has approached the National Highways Authority of India (NHAI) to provide additional funds.

“Since the present scope of work did not provide for raising higher walls, we have approached the NHAI for   additional Rs 134 crore for a 10.8-km stretch and the issue is pending before the arbitration cell. As per the laid procedures, this would take at least a year and a half, pushing further the deadline,” says Debasis Patra, project in-charge.

Until these funds are received, the company is expressing helplessness in doing anything to address this problem, eroding the hill slopes at an alarming pace. Terming as risky the vertical cutting of slopes around 40 feet high, former state geologist Arun Sharma said that water seepage in the excavated rocks causes slip zones, thus triggering massive landslides. 

The angle of repose, which is the maximum slope, measured in degrees from the horizontal, at which loose solid material will remain in place without sliding, should be taken into consideration when excavating a hill slope. A hill continues to erode until it attains its angle of repose, he says.

“In some places, deep cutting of hills should be undertaken by acquiring more land to ensure stability. Otherwise, the hill slopes comprising sedimentary and shale stones will continue to erode for the next four to five years. Other issues like identifying dip and undertaking wire netting on slopes along vulnerable places like the rail track should be undertaken to minimise landslides,” he suggests.

With little monitoring by the state agencies to ensure quality work, these key aspects appear to have been overlooked. Even the concrete structures erected along the hills at some places have failed to remain intact in this rainy season. According to an estimate made by the company, as much as 1.5 lakh cubic metre debris have eroded from the slopes this year and almost a similar amount had eroded last year. While adding considerably to the project cost, this has delayed the completion of this much-awaited project, whose deadline elapsed in March.


ExpertSpeak

The mountain ranges in the state are relatively very young and experience upheaval frequently. This results in landslides during heavy rain. Another major factor for landslides is the presence of faults and thrust plains, making such area prone to landslides. There is no practice of undertaking geological strata study before a road is planned. In most cases, political considerations and meeting the needs of the villagers are the deciding factors, irrespective of the region’s vulnerability to landslides. — Arun Sharma, Retired State Geologist

Adopting grid-based technology to construct roads will help maintain the hill slope and prevent landslides while cutting. In this method, one lane is cut at the higher side for gaining length and then the second lane is constructed 10 m on the lower side. By this method, the cost of construction would get hiked by almost 20 per cent as greater width requires more land. However, with better roads, greater care will have to be taken to avert accidents. — YA Raut, Manager (Technical), NHAI

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