DEVELOPMENT OF TUNNELS

The Company has constructed about 40 km of hydro & highway tunnels in the difficult terrains of Himalayan geology.

Projects In Hand

Dhalli Tunnel Project

The old Dhalli Tunnel in Shimla was constructed in 1852 which is almost 170 years old. Due to the one-way movement in the old tunnel, there used to be traffic jam on both sides of the tunnel. So, to overcome this problem, a new double lane traffic tunnel is being constructed under the Smart City Mission parallel to the old tunnel, with the construction of this new tunnel people will get relief from traffic jams.

The work of “Construction of 2 Lane Road Tunnel parallel to the existing Dhalli Tunnel including all relevant E&M Works, Reconstruction of existing Approach Road and Maintenance at Shimla, Himachal Pradesh under Shimla Smart City Mission on (EPC) Mode” has been awarded to M/s. Sai Eternal Foundation in joint venture with Sai Shakti Solutions LLP. Foundation has completed the excavation of tunnel along with necessary support treatment work like rock bolting, lattice girder installation, shotcreting with consolidation grouting and forepolling etc. in record time (using NATM Technology Without Blasting).

The total length of this tunnel in the form of horseshoe is 159.75 meters, width is 12 meters and the height is 8 meters. In addition to the passage for vehicular movement in the tunnel, pedestrian paths have also been made on both sides of the road, so that people will be able to walk on both sides of the tunnel. The work of this tunnel has been accomplished with such a unique technique in which the inner lining of the wall is made with the synapses of lattice girder and steel fiber mesh. Rock bolts have also been installed to stabilize the inner surface of the tunnel.

The biggest concern in the construction of this tunnel was that the use of blasting technology for the excavation of this tunnel could have caused earthquakes which could further have threatened the nearby and above buildings and also the one old one-way tunnel. Before starting the tunnel work, around 40 buildings were surveyed around and on top of it. During the survey it was founded that some of the buildings built around and above the tunnel are in very poor condition. During this, the department used the latest equipment to measure any movement or displacement around the tunnel. Keeping in view the apprehension prevailing among the people, the department decided to get the tunnel work done by different types of machines and not by using technology. This decision met all the parameters and the tunnel work was completed successfully before the scheduled time. This is the first double lane traffic tunnel to be successfully constructed in Himachal Pradesh with this methodology, which has been successfully built without any disruption in such a dense population. The specialty of this tunnel was that there was zero movement in any building and old tunnel due to the equipment and method used during construction and no damage was caused to any building/building. The construction work of this tunnel started on March 11, 2022. With regular monitoring meetings and clear guidelines and timely review, the work of tunnel was successfully completed ahead of time at an accelerated pace. Thereafter, to prevent leakage of water into the tunnel, geotextile & PVC membrane will be installed on its surface. The surface of the tunnel will be paved and levelled with the help of concrete. The construction work of this tunnel will be completed soon.