Faced with freak dust storm, fragile transmission towers collapse like ninepins

The towers were technically designed to withstand wind speeds much higher than the 115 kmph peak speed during the storm.

What has got the grid managers worried is the large scale toppling of transmission towers.

A record 30 transmission towers either collapsed or were severely damaged across the northern hinterland after Friday’s freak dust storm, highlighting the fragility of India’s grid infrastructure.

What has got the grid managers worried is the large scale toppling of transmission towers, all of which are technically supposed to be designed to withstand much higher gusts of wind than the 115 kmph peak winds that were experienced on May 30.

As per the Bureau of India Standards’ Code of Practice for Design of Wind Loads for Buildings and Structures (IS-875 Part III), the basic design of structures such as buildings in areas around the National Capital Region and most of the northern region should factor in wind speed of 47 metres per second, which works to around 169 kmph.

Additionally, for installations in open areas and high structures such as transmission towers, a margin of 10-15 per cent is to be further built in. For key structures such as high-tension 765kV towers, an extra safety margin of 7 per cent is supposed to have been factored in.

Despite this, an estimated 19 towers of 765kV capacity and another 11 of 400kV and 220kV across three northern states collapsed on account of the dust storm that occurred on Friday evening, with winds estimated to have been blowing at a peak of 92-114.8 kmph from the North-West direction into the northern plains.

In addition, there were at least half a dozen tripping of lines and substations due to faults such as insulators and jumper wires coming loose as the weather system travelled from Punjab across Haryana, and then to Delhi, according to the Northern Region Load Dispatch Centre’s latest outage report.

While the power ministry did coordinate a rescue act across the northern states in the immediate wake of the incident to ensure that power supplies were restored in the affected areas, grid managers are alluding to the larger concern that the transmission tower infrastructure may be “under designed”, especially 765kV transmission towers that are supposed to be designed with additional safety margin.

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This could explain their having collapsed like “ninepins” despite being subjected to wind speeds much below the expected design threshold, officials said.

Anil Sasi

Anil Sasi is the National Business Editor at The Indian Express, where he steers the newspaper’s coverage of the Indian economy, corporate affairs, and financial policy. As a senior editor, he plays a pivotal role in shaping the narrative around India's business landscape. Professional Experience Sasi brings extensive experience from some of India’s most respected financial dailies. Prior to his leadership role at The Indian Express, he worked with: The Hindu Business Line Business Standard His career trajectory across these premier publications demonstrates a consistent track record of rigorous financial reporting and editorial oversight. Expertise & Focus With a deep understanding of market dynamics and policy interventions, Sasi writes authoritatively on: Macroeconomics: Analysis of fiscal policy, budgets, and economic trends. Corporate Affairs: In-depth coverage of India's major industries and corporate governance. Business Policy: The intersection of government regulation and private enterprise. Education Anil Sasi is an alumnus of the prestigious Delhi University, providing a strong academic foundation to his journalistic work. Find all stories by Anil Sasi here ... Read More