"Linear infrastructure is the biggest driver of habitat fragmentation in India." Examine how wildlife mitigation structures help reconcile highway expansion with biodiversity conservation.

Highways split forests into isolated patches. This causes habitat fragmentation, barrier effects and wildlife–vehicle collisions [1]. On NH 715 through Kaziranga, 1,176 roadkills were recorded in a single year (2019) [4]. Mitigation structures let India expand its highways while keeping habitats connected. They work best alongside careful alignment, not as a replacement for it.

How highways fragment habitats

• Direct deaths: on NH 715, about half the roadkill was reptiles, and only 3.48% was large mammals [4].
• Barrier effect: hog deer avoided noisy roadside strips, so their usable habitat shrank even where no animal was hit [4].
• Cut-off corridors: in July–August, animals must cross NH 715 to escape floods and reach the Karbi Anglong hills [4].

How mitigation structures reconcile the two goals

• Structural connectivity: NHAI's October 2026 document reports about ₹19,700 crore spent over five years and more than 2,150 structures built or proposed. These include viaducts, underpasses, overpasses and canopy crossings [1].
• Non-structural measures: guide fencing and noise barriers on more than 300 km, plus speed limits and signs at collision hotspots. These protect road users as well as animals [1].
• Science-based design: NTCA–WII guidelines on linear infrastructure set design norms, such as underpass height at least equal to width [3].
• Proof of use: the NHAI–WII study 'Landscapes Reconnected' recorded 18 wild species and 60 elephant crossings through underpasses on the Delhi–Dehradun corridor [2].

Limitations

• Spending, not results: only about ₹5,250 crore went to animal-only crossings. The 2,150 figure also mixes planned structures with finished ones [1].
• Bias towards big animals: reptile crossings are listed as non-structural, even though reptiles die most on roads [1][4].
• Short monitoring: a 40-day study [2] can miss the July–August peak in roadkill [4].
• Moral hazard: promising crossings can make it easier to justify routing highways through tiger reserves.

Way forward

• Follow the order avoid → minimise → mitigate, as NTCA–WII guidance intends [3].
• Run year-long roadkill surveys before and after construction, and introduce seasonal speed limits on flood-escape stretches [4].

Mitigation structures turn highways from barriers into roads animals can cross. This shows that infrastructure and conservation need not be a trade-off. They will only deliver if forests are avoided first, success is measured by deaths prevented rather than money spent, and designs cover small animals as well as large ones. Used this way, they serve both SDG 9 (resilient infrastructure) and SDG 15 (life on land).