One more building collapsed in Mumbai, resulting in 14 deaths and scores of injuries. Some are believed to be trapped inside the rubble till date. As usual, blame games started by politicians and TV news media screamed at authorities and government demanding accountability. The point is that this latest building is neither the first to collapse nor will be the last. Buildings collapse everywhere in India, especially during the monsoon for obvious reasons. Blame-game politics, demand for accountability and various excuses will be repeated, but the same collapse and resulting fatality and injuries will continue.
This article is not intended to deal with related politics or blame game. I am a civil engineer with more than 30 years of experience in infrastructure projects that include: roads, bridges, buildings, flyovers, railways etc. I will try to explain why buildings or even bridges/flyovers collapse, and how the fatalities can be prevented, in a layman language.
A structure always has a lifetime. Most of the structures are designed for a hundred years. However, there are many reasons for which the lifetime of a structure reduces. For example, if there’s poor construction (due to lack of skill or due to the vested interests of profiteering in using sub-standard materials by the construction manager), then the lifetime of structures will be reduced considerably.
A flyover or a building, however poorly constructed, if not collapsed during the construction, will sustain for decades (30–40 years), instead of an originally designed lifetime of 100 years. But then, one thing must be noted that buildings or other structures never collapse suddenly (except in the case of an earthquake). To put it in more precise terms, before a structure collapses (building or bridge), it gives enough warnings that it will fall.
Let me give you an example. Cover to reinforcement is a vital requirement to ensure that the reinforcements do not corrode due to the weather effect. Reinforcement steel is vulnerable to a mix of water and oxygen, and once reinforcement is rusted, it would continue to induce rusting to all the reinforcement that is inside the concrete. As a result, the steel rods bulge and break the concrete around it. Once corroded, the reinforcement steel loses its load-carrying capacity. But it doesn’t collapse suddenly. First, the concrete will show cracking, then reinforcement will be visible, and then some concrete portion will start falling.
All these are warnings a building gives as if saying “I am going to collapse any time”. People should understand that this situation needs to be rectified. What they do instead is they use some mortar and cover the cracks thinking that the problem is rectified. But the fact remains that the process is only an attempt to hide their failure. It doesn’t restore the load-carrying capacity of the reinforcement. Such shoddy work was also done to Mumbai CST railways over-bridge which finally collapsed. This was an engineering failure because departmental engineers didn’t realise that you can’t restore the load-bearing capacity of a structure cosmetically.
If a portion is under-designed or poorly constructed, in an early stage, it will take all the load. But after 10 or 15 years, it will start showing signs of distress, which in layman terms means the structure isn’t able to take the load. Developing cracks, concrete portions falling down, and many other symptoms can even make a layman realise that something wrong is there. But then people ignore those warnings and departmental engineers usually do a cosmetic repair like plastering the cracked portions or filling the gaps, which is purely done to hide the warning instead of rectifying the structure.
Such structures can’t be rectified. A good structure can be maintained periodically to increase its life. But a defective structure can’t be rectified after it develops snags. In the rainy season, water enters the structure through cracks (even if the cracks are tiny) and accelerate collapsing of the structure. That’s why I say the building collapse at Mumbai is neither the first nor will be the last.
What Can Be Done?
Governments must ensure that all buildings/structures are periodically audited by institutions of repute. For example, ‘Institution of Engineers (India) or IRC (in case of Road related structures) or by NBCC or by IITs (Indian Institute of Technology). All the buildings and structures such as bridges/flyovers etc. must be audited periodically to evaluate the condition of the structure. Urgency must be given to the structures which are giving distress signs as explained above, and to other structures which are more than 40 years of age if there are no visible distress signs.
The independent bodies, as referred above, should give suggestions on whether a structure can be rehabilitated or is beyond rehabilitation. Those structures which can’t be rehabilitated must be barred from inhabiting and should be dismantled with immediate effect. In case a structure can be rehabilitated, then people shouldn’t be allowed to live there till the rehabilitation is completed, and the building declared safe.
In many structures, such as road bridges, caution signs are always provided by the concerned departments such as “This bridge is distressed and heavy loaded vehicles are not allowed”. In some flyovers or bridges, there’s a speed restriction or vehicle restriction, depending on axle loads. Unfortunately, such things are not adopted in buildings—irrespective of the nature of the building— whether it’s public or private.
The conclusion is simple, it may be a bit expensive for auditing, rehabilitation or dismantling, but the question is, are such expenses greater than human life? The governments must deliberate on this.