NHAI launches first National Highways Green Cover Index

A satellite-based, chlorophyll-derived measure of green cover along national highways, built by NHAI with ISRO's National Remote Sensing Centre.

What happened

• The National Highways Authority of India (NHAI) released the first Annual Report on the National Highways Green Cover Index (NH-GCI) 2025-26 on 9 March 2026.
• It is the first time the greenery flanking India's national highways has been measured as a quantitative, repeatable index rather than as anecdotal plantation counts.
• The index was prepared in coordination with the National Remote Sensing Centre (NRSC), the remote-sensing arm of the Indian Space Research Organisation (ISRO).
• It uses space-based, high-resolution satellite sensors to detect chlorophyll content on both sides of highways and converts that into a green-cover percentage.
• The first measurement cycle covered roughly 30,000 km across 24 States for the period July to December 2024.
• The report establishes a baseline; future annual cycles will track year-on-year change in green cover along the same network.

Background & context

Roadside plantation has long been a stated obligation of highway development in India, but it has historically been reported through plantation drives, sapling counts and survival-rate certificates submitted by contractors — figures that are difficult to audit and easy to inflate. The NH-GCI replaces that self-reported plantation accounting with an independent, instrument-based reading of how much living green cover actually exists along the carriageway. The shift mirrors a wider move across Indian governance toward remote-sensing-based monitoring, where satellite data is used to verify ground claims in forestry, agriculture, crop insurance and infrastructure.

The index sits within the institutional relationship between NHAI and ISRO. NHAI, a statutory body set up under the National Highways Authority of India Act, 1988 and operational from 1995, is the nodal agency for developing, maintaining and managing the National Highways network under the Ministry of Road Transport and Highways. NRSC, headquartered at Hyderabad, is the ISRO centre responsible for satellite data acquisition, processing and remote-sensing applications. The two signed a three-year Memorandum of Understanding in January 2024 to apply space technology to highway monitoring; the NH-GCI is one of the products of that arrangement, and the annual cadence is designed to run through the life of the MoU and beyond.

The work also connects to NHAI's broader environmental commitments around highway development — roadside avenue plantation, median and slope greening, and tree transplantation where road widening would otherwise fell mature trees. By giving these activities a single comparable number, the index is meant to convert a scattered set of greening efforts into something that can be tracked, ranked and held to account stretch by stretch.

Two design choices in the index are worth understanding, because they are what make it examinable. The first is the unit of measurement: the Right of Way. The RoW is the full width of land legally acquired for a highway — not just the paved carriageway, but the shoulders, medians, embankment slopes and the verge on either side up to the acquisition boundary. By anchoring the index to the RoW rather than to an arbitrary buffer, the report measures green cover on land that NHAI actually controls and is responsible for, which is what makes a low score genuinely actionable. The second choice is the proxy: chlorophyll. Rather than asking field staff to count trees, the satellite reads the chlorophyll signature of vegetation — the pigment that drives photosynthesis and that healthy living plants reflect in a characteristic way. This makes the reading objective and seasonally comparable, since the same sensor can re-image the same kilometre and detect whether living green cover has grown or shrunk, independent of any human report.

Reading the index at one-kilometre granularity is the third feature that gives it teeth. Because every single kilometre of the surveyed network carries its own green-cover percentage, the report does not collapse into a single national average that hides weak stretches. A planner can see exactly which kilometres are bare and target plantation there, and an auditor can compare next year's reading for that same kilometre. Over successive annual cycles this builds a time series for each stretch — the foundation for any later attempt to rank corridors, set greening targets, or link environmental performance to project review.

For Prelims

• What it is: NH-GCI — National Highways Green Cover Index, the first annual index of green cover along national highways, baseline report for 2025-26.
• Who builds it: NHAI, in coordination with the National Remote Sensing Centre (NRSC) of ISRO.
• Parent ministry: Ministry of Road Transport and Highways (MoRTH); NHAI is the statutory body under it.
• Legal basis of NHAI: National Highways Authority of India Act, 1988; the Authority became operational in 1995.
• Enabling agreement: a three-year MoU between NHAI and NRSC (ISRO), signed in January 2024.
• What it measures: green cover within the Right of Way (RoW) — the legally acquired land strip on either side of the highway — expressed as a percentage of that land under green cover.
• Granularity: reported at one-kilometre intervals, so each kilometre of highway carries its own green-cover figure.
• Method: derived from chlorophyll content detected by high-resolution satellite sensors on both sides of the highway; chlorophyll is the proxy for living vegetation.
• First cycle coverage: about 30,000 km of national highways across 24 States.
• Reference period: July to December 2024; the first report is the 2025-26 annual edition and serves as the baseline.
• Cadence: annual; subsequent cycles will track year-on-year change against this baseline.

For the "how many of these" and "match the pairs" patterns, it helps to place NH-GCI in the family of agencies and instruments it touches. The producing pair is NHAI (statutory body, MoRTH) plus NRSC (ISRO centre, Department of Space). The unit of measurement is the Right of Way; the proxy is chlorophyll; the resolution is one kilometre. A useful comparison is the India State of Forest Report by FSI: both are satellite-assisted green-cover assessments, but ISFR reads remotely sensed forest and tree cover for the whole country on a biennial cycle, while NH-GCI reads only the strip along highways on an annual cycle and is owned by a roads body, not a forestry body. Another sibling in spirit is NRSC's broader remote-sensing portfolio — the same centre supplies satellite inputs for agriculture, land use, disaster support and now highway greening — so a candidate who knows NRSC is the data engine behind NH-GCI can answer linkage questions across multiple programmes.

Why it matters

The index addresses a measurement gap. National Highways are a fast-expanding asset — tens of thousands of kilometres are added or widened each year — and the roadside green belt that accompanies them performs real functions: it absorbs vehicular emissions and dust, buffers noise, stabilises slopes and embankments, lowers surface temperature along the carriageway, and provides a continuous habitat corridor in otherwise built-up land. Until now there was no objective way to confirm whether the greenery promised during construction survived and grew. By converting living vegetation into a per-kilometre percentage that a satellite can re-read every year, NH-GCI makes greening auditable: a stretch that loses cover shows up, and a stretch that improves can be credited.

It also strengthens the accountability chain. Because the reading is independent of the contractor and the field office, it reduces the scope for inflated plantation claims and creates a verifiable basis for environmental clearances, performance review and possibly future incentive design. And it is an example of space technology applied to everyday governance — ISRO's remote-sensing capability put to use not for a marquee mission but for the unglamorous, continuous task of checking whether India's highways are getting greener.

The timing matters for context. The first reference window, July to December 2024, deliberately captures the post-monsoon months, when vegetation in most of India is at or near its seasonal peak — a sensible baseline for a green-cover reading, since it sets the bar against the greenest realistic state of each stretch. Establishing the baseline in 2025-26 means that the second cycle becomes the first true year-on-year comparison, and only from that point can the index report whether highway greening is improving or declining. This is the standard shape of any new index: the first edition is mostly a reference value, and the analytical payoff comes from the trend.

Finally, the index has value as a template. The same NHAI-NRSC method — read a defined land strip with satellite sensors, convert chlorophyll to a percentage, report at fine granularity, repeat annually — could in principle be applied to railway corridors, canal banks, or urban road networks. As a worked example of measurable, technology-verified green infrastructure, NH-GCI is the kind of specific, datable instrument that strengthens an answer far more than a generic claim that "the government is promoting greenery."

For Mains

Syllabus: GS3.14 (conservation, pollution, environmental impact) · GS3.9 (infrastructure — roads) · Linkage L2 (referable).

Related: Environment & Ecology · NHAI / ISRO-NRSC entity hub · this week's cards.