How can satellite-based tools such as the National Highways Green Cover Index improve accountability in environmental compliance for infrastructure projects?

India's National Highway network grew from 91,287 km in 2014 to 1,46,572 km by March 2026 [1]. At that scale, site visits and contractors' own reports cannot reliably check environmental compliance. The NH-Green Cover Index (NH-GCI), built by NHAI with NRSC-ISRO, measures green cover inside the Right of Way (RoW) using satellite imagery [2]. It gives regulators an independent way to check what contractors claim.

How satellite tools strengthen accountability

• Independent verification: NRSC detects chlorophyll through high-resolution satellite sensors. This reduces dependence on contractors' own reports [2].
• Comparability: A standard percentage score for every 1-km stretch allows ranking and targeted interventions across projects and regional offices [2].
• Outcomes over inputs: The score checks whether green cover lasts, not only how many saplings were planted. It supports the September 2026 norms that link provisional completion to planting ≥80% of the RoW and ≥90% survival [1].
• Scalable monitoring: Monitoring has moved from field visits alone to drone and satellite checks [1]. Repeated cycles build a time-series record.
• Transparency: A public annual report lets Parliament, auditors and citizens scrutinise the programme [2].
• Replicability: The same method could check compensatory afforestation under the Forest Conservation Act, 1980 [3].

Satellite (NH-GCI, 1-km)  →  Harit Path (plant-level geo-tag)  →  90% survival check  →  Completion certificate / payment

Fig: A layered chain for verifying compliance

Limitations

• Partial coverage: The first cycle covered only about 30,000 km in 24 States [2], roughly one-fifth of the network [1].
• Quantity, not quality: From space, native mixed stands, single-species rows and weeds can all look "green".
• Net loss hidden: Without a pre-construction baseline, replacing a mature tree with saplings may barely change the score.
• Scale mismatch: The Harit Path app geo-tags individual plants [4], but it is not linked to the km-level index.
• Audit gap: CAG's Bharatmala Phase-I audit flagged RoW and forest-land delays and inaccurate project reports, but reported no plantation findings [5].

Satellite tools turn environmental compliance from a paperwork claim into measurable public evidence. Four steps would make this accountability complete: extend NH-GCI to the whole network, record baselines before construction, link it to Harit Path data, and publish a tree balance (trees lost against trees surviving) for each project. That would give real effect to Article 48A and SDG 15 alongside infrastructure growth.