Delhi Airport Roof Collapse: How Red Flags in T1 'Structural Flaws' Were Ignored

Incidentally, this is not the first time that inadequacies of the Delhi airport’s infrastructure have come to light.

(Photo: Kamran Akhter/The Quint)

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Back in 2009, when Terminal 1 of Delhi's Indira Gandhi International Airport was newly built, Minu CP, the Principal Architect at Bengaluru-based firm Ravi and Minu, wrote a blog on Architecture Ideas criticising the terminal's design.

The design was “susceptible to leaks”, she noted.

Months after the terminal started functioning later, in August 2009, a part of the roof collapsed following heavy winds over 90kmph. Some parts of the terminal developed leaks too after it rained for a few hours with 38.1 mm intensity.

This year, on 28 June, something similar happened. Delhi received 228.1 mm of rainfall – breaking an 88-year-old record. The same morning, at around 5 am, a portion of a canopy at T1’s old departure forecourt collapsed killing 45-year-old Ramesh Kumar – a cab driver from Uttar Pradesh – and injuring at least six other people.

T1 has now been shut for close to 22 days already. Media outlets, quoting sources, have reported that the terminal, which was supposed to become functional again after repairs, might stay closed for almost two more months.

IIT Delhi structural engineers appointed by the Civil Aviation Ministry to conduct an independent enquiry into the incident have reportedly told the Government of India that a thorough audit of the building structure is needed. The Quint had reached out to IIT Delhi for more details, which the latter declined.

Incidentally, this is not the first time that any inadequacies of the Delhi airport’s infrastructure have come to light.

So, two questions arise – why were architects and structural engineers wary of T1's design in the first place, and could the roof collapse have been averted?

‘Not the First Time’

The part of the roof that collapsed on 28 June was built in 2009 – after the GMR group-led Delhi International Airport Ltd (DIAL) took over the airport from the Airport Authority of India.

After the August 2009 roof collapse, architect Hafeez Contractor, who had designed the airport, was quoted by The Indian Express as saying,

“The building’s roof was not designed to take such heavy winds, which were almost tornado-like for 15 minutes. We need to rework the roof design now for a higher wind load.”

The national daily had also quoted a source as saying, “Investigations so far have revealed that the roof had structural flaws.”

Following the incident, DIAL’s COO Andrew Harrison, had told the media,

“Terminal 1D is much higher than other terminals and therefore more exposed to the elements. The airport witnessed unprecedented rains and strong winds and such conditions are difficult to account for.”

However, Civil Aviation Secretary M Nambiar, after the 2009 roof collapse, told mediapersons, "The Directorate General of Civil Aviation (DGCA) will suggest various measures to strengthen the oversight mechanism on development operations and maintenance of new aerodromes and expansion of existing ones."

Now that 15 years later the airport's roof collapsed again, The Quint reached out to Hafeez Contractor to understand if his comment on the need to "rework the roof design now for a higher wind load" was taken into consideration back then.

His office responded, saying, "As given the sensitive nature of this subject and after a careful consideration, we regret to inform you that Mr Contractor won’t be able to talk for the given subject."

While Contractor did not respond, interestingly, he wasn't the only one to have pointed out 'structural flaws'.

Minu told The Quint that back in 2009 when she was reviewing the newly completed T1, "even though, it appeared to be a modern structure with lot of natural light thanks to the number of skylights, I was sceptical about how well the design would survive the elements in the long run."

She further explained,

"Skylights are holes that are punctured into a continuous roof covering. Then the hole is covered with another material like glass which has a different rate of expansion. The resulting joints between the roof material and glass have to be sealed well; and not only that, the sealant has to allow for the expansion during the hot summers and the contraction during the cold winters. Over time, even the best installed skylights are bound to develop leaks and potentially cause roof damage."

Minu went on to add that in a place like Delhi that witnesses extreme weather, "in my opinion, skylights are just asking for trouble."

This has, unfortunately, been witnessed in the terminals time and time again.

In June 2013, when Delhi received 62.8 mm rainfall for a few hours, and in June 2021, when the city received 1,100 mm of rainfall in the span of a day, terminals of the Delhi airport were waterlogged for hours and passengers had to navigate their way through knee-deep waters. At the time, DIAL staffers had to drain the terminal manually till the time the rains stopped.

When The Quint reached out to DIAL, they did not comment on the previous incidents.

Where Did Things Go Wrong at T1?

Sangeeta Wij, Past Vice President (North), Indian Association of Structural Engineers, told The Quint that public spaces that opt for large column-free areas require that the design and material selection be carried out more diligently (preferably using steel) and that the design, execution, and periodic maintenance be of high quality.

Dr Abhay Gupta, Structural Engineer and Director of Skeleton Consultants – who is working on the condition assessment audit of the Lucknow and Jaipur airports – agreed. 

He shared that most airports use tensile fabric membranes for their extended canopies, which are essentially wire structures which can provide critical support.

Dr Gupta, however, said that tensile fabric is "much more vulnerable and weaker than steel, and could have corrosion if not paid attention to."

According to him, what presumably happened was that the rainwater outlet in the canopy was perhaps choked which led to water being accumulated in the tensile fabric canopy. This, he said, indicates that there possibly could have been maintenance issues with some crucial parts not functioning fully.

Both the experts also add that during the investigation, it needs to be studied if there were any maintenance issues in the form of rust or corrosion, and whether the integrity of the structure was compromised due to erratic maintenance.

Minu agrees. She told The Quint, "A proper analysis of the structural design is necessary to understand the cause."

Is Climate Change to Blame for What Happened?

Talking about the recent collapse, a DIAL spokesperson told The Quint,

“While the cause for the collapse of the canopy is being assessed, the primary cause seems to be the heavy rainfall. As per the Indian Meteorological Department on Friday, Delhi Safdarjung had recorded massive 228.1mm of rain in 24 hours (mainly in the early morning hours of Friday).”

But can an extreme weather event be blamed? No, not entirely, said experts.

While Wij said that the rainfall intensities and weather patterns have changed drastically in the last few years, she added that it just puts more emphasis on the need for good design, matching detailing of joints, good execution, and good maintenance.

“Anyone who is designing now needs to take into account that water is not accumulated on the roof for a long period of time. There needs to be adequate and well-sized drainpipes carrying all the rainwater away, ensuring quick and immediate drainage. Sadly, this is not given as much attention as it needs. Effective drainage should be ensured to avoid creating additional loads on the structure.”

Sangeeta Wij

Where does the fault lie though?

Speaking to The Quint, Wij explained that there are some major issues that plague the construction of public infrastructure in India. She said that in the case of any large public project, all aspects – engineering, procurement, and construction – are given to one contractor. The focus is on ‘least cost selection’ since the projects are still awarded on the basis of lowest bidder concept.

However, other countries follow the quality-cum-price system, where the experience of contractors, how many qualified engineers and specialised equipment the contractor has, the quality of his past projects, etc, is given weightage too, said Wij.

These projects also have unrealistic timelines which puts pressure on the design engineer and the architect. In such cases, the vetting of the project is also done by academic institutions and not by experienced structural engineering professionals.

“This system places a disproportionately large emphasis on saving structural cost and somehow managing its on-time completion, and not on technically the most suitable and correct design, detailing, and execution. The traditional way of hiring a contractor through the Central Public Works Department was much better because the latter had in-house competence to check the design,” she said.

Secondly, there is no rigorous system in place to regulate the engineering design and execution as there’s no professional licence for engineers in India and no Engineer's Bill has ever been passed, unlike the mechanism in other countries. 

“While lakhs of crores are being spent on infrastructure projects each year, this is a big lacuna that we don’t have professional engineers overlooking this, who should be paying more attention to the design of joints, rainwater drainage, and accumulation. We need good execution following correct and quality design,” says Wij.

Another thing that demands notice is the periodic upkeep of the structure. Dr Gupta pointed to the need of regular maintenance and monitoring of any critical infrastructure where a huge public footfall is expected, and people’s lives could be at stake. 

“There should be routine inspection in the initial years, and after 5-10 years, all the components of the construction should be checked – not just those that might need repair or are visible to us.”

Dr Abhay Gupta

Terminal 1 usually handles domestic flight operations with IndiGo and SpiceJet aircraft. While T1, T2, and T3 would on average handle 1,400 flights daily, now at least 72 IndiGo flights have been moved to T2 and at least 17 of them to T3 while T1 is under maintenance.