A Road of Many Challenges
The Himalayan range in North India is the youngest mountain range in the world. While they are a dream destination for many tourists, the infrastructure development to meet all the growing demands of this region is equally challenging. The combination of rocky mountains with loose soil strata underneath makes any construction project in this region highly challenging. One such ongoing project is the four-laning of Pandoh Bypass to Takoli section of NH 21, and, Afcons has taken all the challenges head-on to complete this project.
Road connectivity here is not only important to connect the villages and towns, but also for commercial purposes, and, transportation of all the essential commodities. It is also crucial in ferrying millions of tourists to these regions that helps the most important business area - the tourism industry. The new highway will boost tourism with quicker transportation. It will facilitate locals to transport local produce in time to cities and other areas, most of which are perishable food items with limited shelf life. This new highway will be a smoother, all-weather connectivity for the entire region with multi-fold benefits.
Pandoh Bypass to the Takoli section is a busy economic corridor with a crucial power station in between, steep hills on one side, and, deep valleys of the Beas River on the other. The area being a major tourist attraction, the work here needs to be managed without stopping the ongoing traffic. And with 4 Twin Tube Tunnels, 2 Single Tube Tunnels, 2 Major Bridges, 9 Minor Bridges, 1 Elevated Bridge, and, approximately 19 Km road overall to be completed in a span of 3.5 years, the challenges are endless.
One of the most challenging aspects while executing this project is frequent landslides, especially in the rainy season. The role of retaining walls is very important as they not only hold off the sliding mountain sides, but also help maintain the structural integrity. The walls on the river side provide slope protection too. The retaining walls are very high and need to be constructed with very precise planning, within the brief time when it doesn’t rain.
The Power Station Conundrum
In this section, a crucial power station lies right next to the existing national highway. It can never be moved or shut down so the four-laning needs to be executed with those factors in mind. With fixed electrical towers and other electrical infrastructure at the mountain side, it was decided that an elevated bridge will be built above the existing road.
“The elevated bridge is the most critical part of this project. The 823m bridge is the perfect solution to accommodate all the challenges thrown by the power station,” says says Jitender Bhatia, Senior Manager, Planning, Pandoh Tunnel Project.
This also meant a very limited ROW of just 24m. This is not wide enough for the heavy construction machinery required for the construction, all the while live traffic will always remain. Hence pre-cast segments will be used to create the entire bridge structure.
Cut & Cover
In areas with loose soil where the proposed highway will pass, the engineers have planned Cut and Cover tunnels. “The high hills range from 35-50m, and to deal with loose soil underneath, we have to use cut and cover that will ensure that the construction process is smoothly executed, and, the tunnels remain safe in this kind of strata,” explains Bhatia.
High hill cutting, 35-50m above with loose soil underneath, can always cause a potential landslide that can prove disastrous in regular tunnelling methods. To counter this, the team will cut the entire section, create concrete arches for every section they excavate, and then backfill the top of structure to keep the loose soil debris in check.
With a combination of such methods and innovations, the project execution is ongoing at a steady pace. The breakthrough of the longest tunnel in this section has already been achieved and the rest of the project work is running 24/7. Once complete, the highway will transform the area by bringing prosperity to the region in many ways.