The share of the regulated tariff mechanism (RTM) in terms of aggregate outlay of interstate transmission system (ISTS) schemes under construction is on the decline, official statistics indicate.
According to statistics released by Central Electricity Authority (CEA), as of July 31, 2026, the aggregate project cost of ISTS schemes under construction stood at Rs.2,76,671 crore, of which RTM schemes had a share of less than 10 per cent, with TBCB clearly dominating with a share of over 90 per cent.
It is also pertinent to note that the RTM modality is losing momentum even by itself. As of July 31, 2026, the total project cost of under-construction ISTS-RTM projects was Rs.27,330 crore, down from Rs.53,385 crore as of March 31, 2026.
This sharp decline of over 48 per cent is more due to cancellation rather than commissioning of RTM projects.
It may be mentioned that some large interstate schemes that were assigned to Power Grid Corporation of India Ltd (PGCIL) under the RTM mode, now stand cancelled. Prominent of these is the Leh-Kaithal HVDC corridor that was meant to transmit 5 GW of RE power. This scheme, with an estimated cost of Rs.20,774 crore and with completion targeted for March 2031, was under discussion for several years before the Union power ministry decided to put it on hold this year. The project was come up with HVDC technology that was found technically infeasible. Later the deployment of synchronous condensers (SynCon) was proposed but this too was found untenable for practical reasons.
Two large RE evacuation schemes associated with offshore wind farms – Tamil Nadu (500 MW) and Gujarat (1 GW) – have been put on hold due to extremely high anticipated cost, especially with respect to EHV submarine cables. The total anticipated cost of the two schemes was estimated at over Rs.13,000 crore.
Most of the ISTS-RTM projects currently under construction are being implemented by PGCIL with private sector having a very small share of less than 3 per cent. It may be however noted that the indicated cost of ISTS-RTM projects – at Rs.27,330 crore as of July 31, 2026 – is only with respect to those projects that involve new transmission lines or transformation capacity. Projects such as reconductoring of existing lines or bay extension works at existing substations are excluded.
For PGCIL also, RTM projects are gradually weaning in importance in the context of total work-in-hand. As of June 30, 2026, PGCIL’s work-in-hand had an estimated value of Rs.1,75,700 crore, according to PGCIL’s Q1FY27 performance review. Of this, RTM projects accounted for just Rs.25,168 crore or 14.3 per cent.
Today, under-construction ISTS-RTM projects are largely those that involve augmentation of existing assets – typically transformation capacity addition at existing substations. The trend of large greenfield projects being awarded to PGCIL under the RTM route is slowly fading away.
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