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Wildlife underpasses work on Delhi-Dehradun corridor

An NHAI study with the Wildlife Institute of India offers the first hard evidence that animals are actually using the highway's purpose-built crossings.

What happened

The National Highways Authority of India (NHAI), working with the Wildlife Institute of India (WII), Dehradun, released a study titled "Landscapes Reconnected" on the wildlife-mitigation structures built into the Delhi-Dehradun Economic Corridor.
The study documents the first recorded evidence of wild animals moving through the animal underpasses and elevated stretches engineered along the highway, rather than the structures merely existing on paper.
It was carried out on an 18-km forested stretch between Ganeshpur and Asharodi, where the corridor cuts through Shivalik-range Sal forest that is home to tigers, elephants, greater hornbills and king cobras.
Over a 40-day monitoring window, field teams deployed 150 camera traps and 29 AudioMoth acoustic recorders, capturing 111,234 images in all.
Of these, 40,444 images were attributed to 18 distinct wild species using the underpasses, including 60 separate instances of elephants crossing safely.
The finding matters because it converts a design assumption — "if you build the crossing, animals will use it" — into measured, species-level proof on one of India's busiest new expressways.

Background & context

Linear infrastructure — highways, railways, canals and transmission lines — is one of the quieter drivers of biodiversity loss. A road through a forest does not just remove the strip it occupies; it fragments the habitat on either side, cutting a single animal population into smaller, isolated sub-populations and creating a wall of fast traffic that causes roadkill and deepens human-wildlife conflict. The accepted engineering answer is the wildlife crossing structure — underpasses, overpasses (eco-bridges), elevated viaducts and culverts that let animals pass under or over the carriageway. India has begun retro-fitting and designing these into new alignments, but the harder question has always been whether the animals genuinely adopt them. "Landscapes Reconnected" is significant precisely because it supplies that downstream evidence.

The Delhi-Dehradun Economic Corridor is a roughly 210-km greenfield expressway shortening the Delhi-Dehradun journey, built by NHAI under the Ministry of Road Transport & Highways. Its sensitive section runs through the Shivalik foothills — the outermost, youngest and lowest of the Himalayan ranges — and along the edge of the Rajaji landscape, a known elephant and tiger habitat. To let this terrain stay permeable to wildlife, the corridor's Ganeshpur-Dehradun segment was engineered with one of Asia's largest elevated wildlife corridors, raising the road on piers so that the forest floor and its animal movement continue underneath.

The study partner, the Wildlife Institute of India (WII), is the natural choice for this work. WII is an autonomous institution established in 1982 and headquartered at Dehradun, functioning under the Ministry of Environment, Forest and Climate Change (MoEF&CC). It is the country's premier training, research and advisory body on wildlife science — it runs courses for forest officers, carries out the technical backbone of exercises like the all-India tiger and elephant estimations, and advises on mitigation design for exactly this kind of infrastructure project. Reading the camera-trap and acoustic data into species-level conclusions is core WII competence.

It helps to place WII in the wider institutional family so the names do not blur in an exam. WII sits alongside the other MoEF&CC research and field institutions: the Zoological Survey of India (ZSI, est. 1916, Kolkata) for animal taxonomy, the Botanical Survey of India (BSI, est. 1890, Kolkata) for plant taxonomy, the Forest Survey of India (FSI, Dehradun) which produces the biennial India State of Forest Report, the Indian Council of Forestry Research and Education (ICFRE, Dehradun) and the G.B. Pant National Institute of Himalayan Environment. WII's distinctive niche among these is applied wildlife biology and conservation training — habitat, populations and the science of human-wildlife coexistence — which is why a road-permeability question lands with it rather than with a regulator or a survey body.

The terrain itself is worth knowing for Prelims. The Shivaliks (also spelt Siwaliks, and called the Outer Himalayas) are the southernmost and geologically youngest Himalayan range, formed largely of soft, unconsolidated sediments eroded from the higher mountains. They are fragile, prone to erosion and landslides, and ecologically rich — carrying moist and dry deciduous Sal (Shorea robusta) forest that supports elephants, tigers, leopards, sambar, spotted deer (chital), nilgai and a wide bird and reptile community, including the greater hornbill and the king cobra named in the report. The broader Shivalik-Terai-Bhabar belt is one of India's most important elephant landscapes, which is exactly why severing it with an expressway needed careful mitigation.

For Prelims

Report & authors: "Landscapes Reconnected" — by NHAI (Ministry of Road Transport & Highways) with the Wildlife Institute of India (WII), Dehradun.
Study site: 18-km Ganeshpur-Asharodi stretch of the Delhi-Dehradun Economic Corridor, in the Shivalik range, Sal-forest habitat.
Mitigation infrastructure: the corridor section carries 10.97 km of animal underpass, including one of Asia's largest wildlife elevated corridors at an average height of 6-7 m.
Three study zones / terrains: Ganeshpur-Mohand, Mohand-Asharodi and Asharodi-Mohabewala, spanning riverbed, hilly terrain and Sal forest.
Method: 40-day monitoring · 150 camera traps + 29 AudioMoth acoustic recorders · 111,234 total images.
Result: 40,444 images of 18 unique wild species; golden jackal most frequent, then nilgai, sambar and spotted deer; 60 elephant crossings.
Behaviour finding: generalist species (golden jackal, wild boar) habituate to traffic noise; sensitive species (elephant, spotted deer) prefer lower-sound segments — so acoustics, not just structure, shape use.
WII basics: autonomous body under MoEF&CC, est. 1982, Dehradun — a research/training/advisory institute.

What it is NOT: WII is not a statutory regulator and not a constitutional body — it does not issue clearances or run wildlife law. The bodies that regulate are different: the National Board for Wildlife (NBWL), chaired by the Prime Minister, is a statutory body under the Wild Life (Protection) Act, 1972; the National Tiger Conservation Authority (NTCA) is the statutory body for tiger reserves; the Central Zoo Authority (CZA) oversees zoos. WII supplies the science these bodies and project authorities act on. Likewise the "elevated corridor" here is a civil-engineering wildlife crossing, not a notified "wildlife corridor" in the legal-protected-area sense, and not an eco-sensitive zone.

The crossing-structure set (for "match / how many" questions): wildlife mitigation on roads uses underpasses (animals pass below the road), overpasses / eco-bridges or green bridges (animals pass over a vegetated deck), elevated viaducts (the whole road on piers, as here), culverts (for small fauna and drainage) and canopy bridges (for arboreal species). India's other well-known examples include eco-bridges and underpasses on NH-44 through the Pench-Kanha (Pench Tiger Reserve) corridor in Madhya Pradesh / Maharashtra — the most-cited domestic peer to this Delhi-Dehradun work.

Why it matters

India is building roads and railways at scale through landscapes that are also wildlife habitat, and the Shivalik-Rajaji belt is one of the most contested of these — a corridor for the largest land mammal in Asia, the elephant, and a tiger range besides. When a highway severs such a belt, two harms follow: direct mortality (animals killed crossing) and genetic and demographic isolation (sub-populations that can no longer mix, breed or recolonise, which over time weakens their viability). "Landscapes Reconnected" addresses both: 60 documented elephant crossings and 18 species using the underpasses are evidence that the structures keep the landscape permeable, so animals on the two sides remain one connected population.

The behavioural nuance is the more useful takeaway for policy. The data show that noise — not just the physical gap — governs whether sensitive animals use a crossing. Generalists tolerate traffic sound and adapt quickly; elephants and spotted deer steer toward quieter segments. That tells planners the placement, dimensions and acoustic shielding of a crossing matter as much as its existence, and gives a feedback loop: monitor, learn, redesign. For UPSC, this is a clean, current, Indian case of development and conservation being reconciled by design rather than traded off — exactly the framing GS3 environment answers reward.

For Mains

Exemplification

A concrete Indian example of infrastructure-wildlife coexistence: an expressway kept ecologically permeable by underpasses and an elevated viaduct, with measured proof that animals use them.

Substantiation

Hard data points for an environment answer — 40,444 images, 18 species, 60 elephant crossings, 10.97 km of underpass, 6-7 m elevated corridor — to move a claim from assertion to evidence.

Way-forward

Argues for mandatory wildlife-crossing design + post-construction monitoring (camera traps, acoustics) as a standard step in EIA and project appraisal, with acoustic shielding for sensitive species.

Problematisation

Surfaces the underlying problem the structures answer — habitat fragmentation, roadkill and population isolation from linear infrastructure in fragile foothill ecosystems.

Deploys into: conservation vs. infrastructure trade-offs · environmental impact assessment and mitigation (GS3.14) · linear infrastructure and habitat fragmentation · human-wildlife conflict in the Shivaliks · sustainable highway/railway planning (GS3.9).

Ministry of Road Transport & Highways · 2026-04-10 · PRID 2250714 · PIB source ↗

Related: Wildlife Institute of India (entity hub) · Environment & Ecology · This week's cards