Why bridges keep falling across India

About 2,000 bridges are reported to have failed in India during 1977-2017. One essential remedy would be a systematic bridge health monitoring system with regular inspections
Why bridges keep falling across India
Express illustration | Mandar Pardikar

“London Bridge is falling down,

Falling down, falling down,

London Bridge is falling down,

My fair lady.”

The popular English nursery rhyme treats a bridge falling as a matter of little consequence and something almost amusing. But for the builders, bridge failure is a matter of very serious concern. Bridges being vital and busy transport links, their failure can result in a grievous loss of lives and money, and are blots on the civil engineering profession.

Unfortunately for us, the failure of bridges has become routine, with alarming repetition.  They happen during construction, after construction, with traffic, and during different stages of its service life. Failure during construction is generally due to the use of poor material, poor workmanship, or inadequate supervision. Failure during service is due to poor upkeep, or rather, the absence of inspection and maintenance, and a failure to remedy observed defects in time.

Bridges, particularly long-span ones, are undoubtedly some of the man’s greatest physical creations. Some of them have become icons for their cities—the Tower Bridge for London and Howrah Bridge for Kolkata. And yet, some 2,000 bridges are reported to have collapsed in our country between 1977 and 2017, and the rate of failures is only climbing.

The opening of a bridge is celebrated with a lot of fanfare in the presence of politicians and bureaucrats, only to be forgotten thereafter. The engineers responsible are only visible and called upon to explain failures and assign responsibility to some lower-level minions.

Bridge failures continue to happen across the world as well; some of them become case studies for the analysis of causes and learning for future builders. There are classical cases like the collapse of the Tacoma Narrows Bridge in western US, the live video of which spurred the study of aerodynamics for bridges across the world.

The failure of the West Gate Bridge near Melbourne around 1970 caused by the collapse of a steel box girder caused the entire engineering community to wake up and come up with new rules for design. (Very few know that this accident almost derailed the ongoing Second Hooghly Bridge Project in Kolkata.)

Failures are openly discussed and young engineers get the opportunity to learn from them, unlike in our country where failures are hushed up and the reports of inquiry committees never get publicised. The causes of failure therefore remain as an enigma to the public.

Bridges, being important and costly structures, are given considerable attention during their planning and design. The design usually is carried out by a set of planners and designers—in-house, or from an organisation of consultants—and then carefully checked by another set of professionals.

In the case of many important ones, they are also proof-checked by academics from nationally-recognised bodies like the Indian Institutes of Technology or National Institutes of Technology. Bridge failures due to faulty design are somewhat rare. It is the completed structure, with its service loads, that is given all the attention.

During construction, when the bridge structure is in various stages of formation and is therefore unstable, it is vulnerable to failure. Rarely are all these stages analysed by competent designers. This aspect is often left to the construction team with limited design capability.

Since construction continues over long periods, and often gets delayed due to various reasons, attention on the work slackens, leading to failures. The original designers, who are the ones aware of the full analysis, are seldom kept linked to the project during its construction progress.

The other major deficiency in our system is the very limited (or no) attention paid to the structure during its long service lifespan. There is seldom a maintenance plan with a defined inspection schedule, prepared and handed over to the authorities responsible for the upkeep of the bridge, by the authorities who plan and build it.

This task is best prepared by the original designers—who are in the know of the vulnerable areas of the structure that need careful inspection—but they are seldom assigned this task. Ignorance of the vulnerable points in a structure leads to a lack of attention to them, and their deterioration or eventual failure.

It is not uncommon to find concrete bridges in urban areas from which strong, invasive plants like banyan start growing, but such occurrences are completely ignored by the authorities (and by bridge users like us) till the damage becomes too difficult to remedy. It is strange, but true, that there is no standard remedy for eradicating such harmful growths in the maintenance handbook of any of the authorities.

Every bridge authority has strong design and construction teams, but hardly any of them has a defined, trained team for sustained maintenance work who would regularly report on bridge conditions. Institutions like the Indian Railways have well-manned maintenance departments, and this is reflected in fewer cases of bridge failures on their part.

To add to the list of causes of failure is our system of accepting only the least-cost tenders, even for critical items like bridges, which encourage poor quality of construction materials and workmanship. Such poor quality gets accepted, of course, with our environment of corruption and lack of accountability that has penetrated our society. A case in point is the Morbi pedestrian suspension bridge in Gujarat, the collapse of which resulted in the death of 141 people—the tender for its upkeep was awarded to a firm that had no previous experience in bridges, much less in suspension bridges.

We have identified enough causes of failure, but where lies the solution for this endemic problem that affects our construction environment? Some of the desired actions lie in introducing systematic and scientific bridge health monitoring systems that will define the protocol for regular inspection, testing, reporting and remedial actions for restoration. Responsible authorities have to build up trained teams for the specialised tasks of bridge repair and strengthening, with a complementary system for regular updating of the expertise of such teams.

It is time to go beyond accusations and take concerted action. Being a riverine country, we have a great history of bridge building. We need to build back our lost glory.

(Views are personal)

Amitabha Ghoshal | Former President, Consulting Engineers Association of India, & lifetime achievement awardee, ING, International Association for Bridge and Structural Engineering

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