Environmental, social costs of Vizhinjam port railway tunnel to be higher than anticipated

The proposed rail tunnel from Vizhinjam.

The State government’s decision to construct a railway tunnel to Vizhinjam International Seaport costing over ₹1,500 crore through a densely populated region, despite the availability of an alternative land alignment, has raised eyebrows among many, with experts and members of the public questioning its environmental and social costs against the backdrop of the State government’s stated commitment to sustainable development.

The proposed tunnel between Balaramapuram and Vizhinjam to provide rail connectivity to Vizhinjam International Seaport has triggered serious environmental and land stability concerns in the region. The project, which is set to become the State’s second major tunnel project and the country’s third-longest railway tunnel, has been disputed by experts regarding its feasibility beneath the Vizhinjam-Balaramapuram road, who termed it potentially unviable given the region’s fragile geology, soil types and high population density.

Dr. V. Nandakumar, former head of the Natural Hazards Research Group and former director (In charge) of the National Centre for Earth Science Studies, said no comprehensive study involving competent national institutions appeared to have been conducted on the geological formations along the proposed 10.7-km alignment, variations in soil types or the east-to-west groundwater flow before the project was taken up.

Drawing on more than three decades of field experience, Mr. Nandakumar said most stretches of the proposed alignment are likely to pass through geologically weak terrain. Beneath the top layer of laterite, the subsurface is expected to comprise of decomposed lithomargic clay interspersed with hard rock in some locations. Other sections consist of inconsistent red soil underlain by layers of clay and sand. Such formations, according to him, are unsuitable for a tunnel carrying container trains weighing several tonnes.

The proposed alignment also passes through some of the most densely populated areas of Thiruvananthapuram district, where a large section of the population depends on open wells for drinking water. He warned that the impervious concrete tunnel structure, laid at a depth of around 30 metres, could act as an underground barrier, disrupting the natural movement of groundwater. This could eventually cause wells to dry up in an area already facing water scarcity.

He also flagged the risk of vibrations generated by heavy container trains passing through tunnels bored into weak soil. Such vibrations could damage existing structures, ranging from large buildings to smaller houses, causing cracks and, in extreme cases, structural collapse. Land subsidence and building damage could pose long-term risks along the entire stretch, he cautioned.

He also opined whether authorities had adequately explored an alternative alignment through lower-lying areas, including the fringes of the Pallichal-Mudavoorpara paddy fields, which is elevation-wise 10 m lower than the proposed tunnel alignment, which is 30 m below the road surface and almost having a parallel elevation with the port and the Trivandrum- Nagercoil rail link. Such a route, according to him, could avoid potential hazards to densely populated areas and minimise risks to existing structures, groundwater resources, environmental stability and local livelihoods.

It could also reduce construction and maintenance costs. A surface-level alignment would also offer greater scope for future track doubling and expansion, which would be difficult to achieve with the proposed tunnel, he said. The project in its present form could destabilise the region and may disrupt the livelihoods of millions of people living along the Balaramapuram-Vizhinjam corridor. The land above the tunnel, including the buffer zone, could remain locked subject to restrictions on development, building permits and other uses. This also may even affect property ownership and transfer rights. The disposal of excavated rock and soil generated during tunnelling could pose another major environmental challenge.

He urged the government to reconsider the tunnel proposal and instead opt for an overland railway alignment after establishing its economic viability. Senior government officials said they selected the alignment as the shortest route from the existing railway lines to the port, although an overland alignment with relatively lower cost is available through a paddy field in the region.

Published - November 12, 2026 07:00 am IST