Introduction
Road construction in mountainous regions is a complex and challenging endeavor, requiring careful
planning and execution to balance the needs of infrastructure development with environmental
conservation. The preliminary design stage is a critical phase in this process, as it sets the foundation for
the project's feasibility, and environmental impact assessment. During the design, in the case of KTFT
Expressway, it was noticed the survey profile has shifted from the tender design. The shift in survey
results raises concerns about the environmental implications, particularly in terms of ecosystem
disruption. It has become inevitable to change the alignment slightly, potentially making the project
more ecologically and environmentally friendly.
Design Standards
Survey Changes
According to the contract, it was mandatory for the contractor to conduct the engineering survey for
construction purposes, which is essential for both preliminary and detailed design stages. The survey
was conducted by our team and subsequently jointly verified by the ER team on 05.06.2024. During the
preliminary design phase, it became evident that there had been a shift in the survey results. This shift is
illustrated in the accompanying figures, demonstrating the changes in ground profile:
Fig: Shift in the vertical levels along the Main Alignment
Impact on Cross-Sections and RoW
The shift in survey results has led to a slight change in the alignment of the proposed road, portal
locations, bridge locations etc. It also affected the cutting heights which resulted in affect on the RoW,
which may lead to increased adverse effects on sensitive habitats and ecosystems, tree cutting.
Environmental Impact
Ecosystem Impact
One of the primary concerns regarding the road alignment is the potential for habitat disruption and
ecosystem fragmentation. The mountainous region in which the road is being constructed is home to a
flora and fauna, many of which are adapted to the unique ecological conditions of the area. The
construction of the road, with high cutting heights, will inevitably lead to the destruction of vegetation.
This may have an adverse effect on the ecological balance.
Soil and Water Quality
The construction of roads in mountainous areas can also have significant impacts on soil and water
quality, particularly in areas with steep slopes and high rainfall. The removal of vegetation and the
disturbance of soil can lead to increased erosion and sedimentation, which can have detrimental effects
on nearby streams, rivers, and lakes. High cutting embankments unnecessarily may also contribute to
erosion and sedimentation in rivers, particularly during heavy rainfall events.
Recommendations
Design and Engineering Improvements
To mitigate the environmental impacts of the project, it is essential to incorporate sustainable design
practices that prioritize the conservation of sensitive habitats and ecosystems.
For the same, keeping the geometric standards same, the portal locations for the tunnel are planned as
per the geological conditions and the minimum cover requirements over the tunnel, while keeping the
main alignment as original. The same may be referred from the report – KTFT-CP8B-GEN-R005.
For the bridge locations, the spans have been readjusted to accommodate the survey changes keeping
the original alignment. The same may be referred from the report – KTFT-CP8B-GEN-R005
For the right bifurcation alignment, during the preliminary design, the alignment horizontally has been
shifted slightly from chainage 14+760m to 15+780m to accommodate the survey changes and make it
environmentally friendly. The geometric standards have been followed as per the Tender Design and the
same curve radii as in the original alignment are adopted for the final proposed alignment. On a positive
note, for making the alignment smoother, one curve radius has been increased to 1800m from 250m.
Preliminary Design Start
