Frequent landslides on Parwanoo highway a headache for NHAI, motorists

Ambika Sharma

Tribune News Service

Solan, January 15

Recurring landslides have become a major headache for the private company four-laning the 39-km Parwanoo-Solan section of the National Highway (NH)-05 where help of the Geological Survey of India (GSI) was being taken to suggest suitable interventions.

A stretch of two to three kms on this section was especially vulnerable to landslides owing to the weak soil strata where excavation of the hill led to crumbling of mounds of earth.

The National Highways Authority of India (NHAI) has now sought the help of the GSI to suggest a permanent solution as the four-laning work was at an advanced stage. About 80 per cent would be completed by March end.

Landslides have not been contained at several sites like near Datiyar at Dharampur, near Koti railway line, etc, as loose soil coupled with big boulders continue to flow down the hill. Though protection works like rock bolting, shortcrete, etc., have been undertaken besides raising breast walls to contain the landslides these have failed to yield the desired result.

Landslides from a site near a petrol pump at Dharampur have specially become unmanageable due to the vertical cutting of hill. Several houses lying atop the hill have developed cracks. Despite making use of engineering technologies like shotcrete, where a wet mixture of aggregate and portland cement is sprayed over the affected site, the hill continued to erode.

The maximum landslides had occurred during the rains. Arun Sharma, former State Geologist, said that 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 this angle.

Dinesh Punia, an official from the NHAI, said the landslide-prone sites suggested by the private company executing the four-laning work, GR Infraprojects, were inspected by a team of GSI officials. Their report was now awaited. This was the second visit of the GSI team in the recent months.

NHAI looks to GSI for solution

• Landslides have not been contained at several sites like Datiyar at Dharampur, near Koti railway line, etc. as loose soil coupled with big boulders continue to flow down the hill. 
• Though protection works like rock bolting, shortcrete, etc., have been undertaken besides raising breast walls these have failed to yield the desired result.
• Landslides from a site near a petrol pump at Dharampur have specially become unmanageable due to the vertical cutting of hill.
• The NHAI has now sought the help of the GSI to suggest a permanent solution.