Survey to study stability of slopes on Solan highway

Ambika Sharma

Tribune News Service

Solan, October 21

In a bid to ensure the stability of the excavated slopes along the Parwanoo-Solan section of National Highway (NH)-05, a technical survey has been undertaken by the geologists.

The move was initiated by officials of the NHAI as there were reoccurring landslides at several places on the 39-km highway due to vertical cutting of slopes. The survey will assess the need to devise additional measures to ensure that the four-laned highway did not suffer from repeated landslides after its completion.

These slides especially occur during the rains. They have put a question mark on the stability of the road at certain places like Chakki Ka Mor, near Sanwara, Jabli, near Kumarhatti, Saproon Chownk, Dharampur, etc.

Though engineering techniques like shot crete and rock bolting have been put to use at some such sites these have failed to work at places like Dharampur, Sanwara, etc., owing to fragile strata. Shot crete is the process of placing concrete to achieve high strength and low permeability while rock bolting is a type of drilled soil nail or anchor used when the ground to be stabilized consists mostly of rock materials. The use of these techniques is supposed to help contain large-scale erosion on rocky or semi-rocky surface.

“The study will ascertain whether additional measures were required to be implemented on certain sites prone to landslides” informed Balwinder Singh, project manager, GR Infraprojects, which was executing the four-laning work.

“We are awaiting the outcome of this survey as it will help us determine what more is required to be done to strengthen the excavated slopes.”

The officials of the GR Infraprojects have also demanded an additional Rs 33 crore for raising higher breast walls on about 12 kms area which are landslide prone. The NHAI officials were yet to take a decision on granting this cost. As per the project design, breast walls of 1.5 m to 3 m have been raised but since vertical cutting has been undertaken on almost 30 to 40 feet slopes, they were vulnerable to slides at places where the strata was loose.

With about 94 per cent of the project having been completed, the officials hoped to complete the project by March 2021. The work, which began in September 2015, was supposed to be completed within 30 months. It was, however, running behind schedule and has taken almost double the time. Though the project cost has been pegged at Rs 748 crore, it has been enhanced by several crores owing to the delay.