The National Highways Authority of India (NHAI) has begun constructing a viaduct to permanently address the recurring sinking of a service lane near the police lines on the Solan-Shimla highway. The Rs 13-crore project was awarded to Hisar-based Kisan Construction Company on June 30.
Recurring Subsidence Since 2021
The service lane was built as part of the four-laning of the Solan-Shimla highway in 2021 to provide access to residential areas below the main carriageway. However, it has been plagued by repeated land subsidence, with even light showers causing sections of the road to sink by several inches. Loosened soil and debris slide downhill, blocking the road to New Kather and inconveniencing residents. Cracks often reappear within days of repairs, indicating deep water seepage due to the absence of an effective drainage system. A temple located below the service lane is also vulnerable to damage from sliding debris.
Geotechnical Investigation and Viaduct Design
To find a permanent solution, NHAI conducted a detailed geotechnical investigation and decided to construct a viaduct. The proposed 150-metre elevated structure will consist of three 30-metre spans, expected to stabilize the affected stretch and eliminate the recurring subsidence. NHAI Project Director, Shimla, Anand Dahiya stated that the project is expected to be completed within 18 months. Construction will begin after the diversion plan for the service lane receives approval from the Indian Institute of Technology (IIT), Patna, which earlier carried out the geotechnical investigation and is familiar with the site's technical requirements.
Root Causes and Impact
The subsidence has been attributed to inadequate geotechnical investigation and improper assessment of the terrain before construction. Despite repeated repairs, the problem has remained unresolved, with every rain spell aggravating the situation. The viaduct aims to provide a lasting solution to the persistent issue that has affected residents and infrastructure since the highway was four-laned.
