CHENNAI: Amid the ecologically fragile Western Ghats, the proposed Puliyarai-Edamon economic corridor has sparked a fresh debate. Environmentalists have already raised red flags warning that the project is a serious risk to wildlife habitats and mountain ecosystems.
The highway project seeks to upgrade connectivity along the NH-744 corridor between Puliyarai in Tenkasi district and Edamon in Kerala. The alignment passes through one of the most environmentally sensitive stretches of the Western Ghats, a UNESCO World Heritage site and one of the world’s eight "hottest hotspots" of biodiversity.
The most critical concern lies in a narrow bottleneck section where the proposed alignment intersects the Shendurney Wildlife Sanctuary in Kerala and the Nellai Wildlife Sanctuary in Tamil Nadu.
Environmental experts warn that expanding the existing surface highway into a four or six-lane corridor could fragment wildlife habitats and disrupt crucial migration routes used by elephants, tigers and several smaller mammal species.
Planners have proposed an alternative engineering approach involving underground tunnels and elevated viaducts. According to preliminary project details, about 10.12 km of the corridor will pass through twin tunnels drilled through mountainous terrain, enabling the highway to run beneath the forest canopy rather than cutting through it.
The tunnels are expected to have a diameter of about 11 metres, requiring large-scale drilling through hard rock formations. Experts note that such tunnelling typically involves heavy blasting techniques and detonators to break through rock layers. Environmentalists caution that repeated blasting could generate strong vibrations that may disturb wildlife habitats and potentially affect the stability of fragile hill slopes.
In addition to the tunnels, the project design includes about 18 high-level viaducts in sections where tunnelling is not feasible. These elevated structures are intended to allow wildlife movement beneath the road and help maintain ecological connectivity between the two forest reserves.
However, activists argue that the scale of construction activity itself could cause irreversible damage to the ecosystem.
The Western Ghats are a crucial watershed for South India, feeding several rivers and streams that support agriculture and drinking water needs. Large-scale excavation and construction could trigger soil erosion, landslides and sedimentation in nearby water bodies.
The project's greenfield alignment has been designed to avoid the most rugged terrain and largely passes through commercial plantations of teak, rubber and eucalyptus rather than untouched rainforest areas. Even so, project estimates indicate that nearly 23,500 trees may be cut during construction.
Environmental activist Osa Kalidas said mountain ecosystems are highly sensitive and require careful protection. He pointed out that the Western Ghats serve as a major water source for southern India and therefore require the highest level of conservation.
Kalidas also noted that the Western Ghats are globally recognised as one of the world's most significant biodiversity hotspots. He added that the proposed road passes through two wildlife sanctuaries between Kerala and Tamil Nadu and could indirectly affect the ecosystem of the Kalakkad Mundanthurai Tiger Reserve.
He said a team of environmental activists plans to visit the region to conduct a field assessment and release a detailed report on the potential ecological impact of the project.
Meanwhile, the National Highways Authority of India (NHAI), which is executing the project, applied for forest clearance for the proposed corridor in January. Officials said the proposal is currently under review and the file is pending with the District Forest Officer in Tenkasi.
Estimated to cost around Rs 5,100 crore, the Puliyarai-Edamon corridor has become a focal point in the larger debate on balancing infrastructure development with environmental protection in the Western Ghats. Environmental groups have urged authorities to undertake a comprehensive ecological assessment before granting final approvals.
Nearly 23,500 trees may be cut for the project
The project intersects Shendurney Wildlife Sanctuary (Kerala) and Nellai Wildlife Sanctuary (TN)
The proposed tunnel will have a diameter of 11 metres
Excessive drilling in the mountain region will be required
Repeated blasting and following heavy vibrations can disrupt the ecosystem
Migration routes of tigers, elephants and several smaller mammals fall under risk
The effects might also reflect in the Kalakkad Mundanthurai Tiger Reserve
