Weak Soil and Trapped Water Identified as Primary Culprits in Lucknow-Kanpur Expressway Failures
NEW DELHI – An expert assessment conducted by an Indian Institute of Technology (IIT) Kharagpur professor has revealed that the widespread premature failures, including significant slippage, on a crucial stretch of the Lucknow-Kanpur Expressway are primarily attributable to the use of weak and highly plastic soil beneath the roadway. This groundbreaking preliminary investigation sheds light on the foundational deficiencies impacting the longevity and stability of this vital infrastructure project.
The assessment, which meticulously examined severely damaged portions of the expressway, concluded that the fundamental issue lies not with the thickness of the various road layers themselves, which showed no major deficiencies, but with the underlying soil. The report highlights that the presence of "plastic soil"—defined as soil that can be easily molded when wet—is a significant contributing factor to the observed structural instability.
Further exacerbating the problem is the issue of trapped water. The investigation found that water is generally present at the level of the lower concrete layer and in the soil beneath it. While widespread accumulation of water in the upper layers of the road was not observed, significant waterlogging was prevalent in deeply depressed sections. This issue is partly attributed to the unpaved portions of the shoulders, originally designed for future expansion, which appear to be restricting adequate drainage. The report specifically points to a layer of soil positioned between the concrete drainage layer and the hard shoulders as a potential impediment to water movement, consequently slowing its flow into the designated drainage system.
However, the expert clarified that while water presence is a concern, it alone cannot fully explain the severe nature of the failures witnessed. The use of highly plastic soil is deemed one of the primary drivers behind the expressway’s early deterioration. The report also raises critical questions regarding the compaction of this soil and whether the actual strength of the road’s base layer aligns with the assumptions made during its original design.
In response to these findings, the National Highways Authority of India (NHAI) has announced a target to complete remedial works by the end of September. As a temporary measure, toll collection on the entire expressway has been suspended.
The expert panel has put forth several key recommendations to address these systemic issues. For stretches experiencing major depressions and slippage, a complete rebuilding from the bottom up has been advised. This reconstruction is deemed particularly crucial where tests indicate that the strength of the underlying soil is substantially below the levels assumed in the initial design.
Beyond immediate repairs, the assessment strongly recommends a comprehensive and detailed survey to identify all stretches containing weak or highly plastic soil as a matter of urgency. This survey should be complemented by thorough tests to assess the actual strength of the highway and determine whether additional strengthening measures are required.
The expert assessment underscores that the timely identification and effective resolution of weak soil issues are paramount to preventing further premature failures and ensuring the long-term durability and safety of the Lucknow-Kanpur Expressway. These findings call for a re-evaluation of current construction practices and material selection for critical infrastructure projects across the nation.
