Bengaluru’s concrete problem

As we wade into another monsoon season, our once Garden City, Bengaluru, is fast becoming a concrete capital, much like the rest of the country.

Name any development/infrastructure project and the chances are that it involves large amounts of concrete. The white-topping of roads, the reclamation of the rajakaluves, the smart city projects -- all are exercises in engineering in concrete.

The reality that we have just survived a pandemic and that we need to safeguard the planet by engaging in less polluting building methods seems to have been forgotten.

Over the past century, concrete has offered city governments (and the engineers that run them) an inexpensive and simple way to build cities. Dams, bridges, ports, city halls, university campuses, shopping centres are all testament to the power of concrete engineering. The politics of concrete funds the campaigns of politicians; the result is the relationship of politicians, bureaucrats and construction companies perpetuating environmentally and socially questionable infrastructure projects and ‘cement-fests’.

Concrete is one of the most polluting materials on earth. Yet, after water, it is the most widely-used substance. It is the language of engineering and modern development in most urban centres. If the cement industry were a country, it would be the third-largest carbon dioxide emitter in the world, with some 2.8 billion tons, surpassed only by China and the US. It suffocates vast tracts of fertile soil, chokes rivers, clogs habitats, and desensitises us from what is happening outside our urban fortresses.

The problem with concrete is that while it can resist nature for decades, events like the annual floods of Bengaluru and Chennai have become all the more severe because concrete streets cannot soak up the rain like a floodplain, and stormwater drains prove woefully inadequate for the new extremes of a disrupted climate.

Concrete also magnifies the extreme weather it shelters us from. It is responsible for 4-8% of the world’s CO2. Other environmental impacts include sucking up almost a tenth of the world’s industrial water, adding to the heat-island effect by absorbing the warmth of the sun and trapping gases from car exhausts and air-conditioner units, worsening the problem of silicosis and other respiratory diseases.

Limestone quarries and cement factories are also pollution sources, as are the trucks that ferry materials between them and building sites. Sandmining, destroying much of the world’s beaches and river courses, is also on a catastrophic scale. The biodiversity crisis is being driven by the rapid destruction of nature and the development of industrial estates and residential blocks. The benefits of concrete are now being outweighed by its environmental downside.

There is only so much concrete you can serviceably lay without ruining the environment. Today, unfortunately, traditionalists and environmentalists are routinely ignored. The engineers in charge of producing masterplans and detailed planning reports pay little heed to the classic aesthetic ideals of harmony with nature and an appreciation of the environment. In Bengaluru, we are now drowning in a river of concrete sludge. We are seeing floods with just one day of rains -- mostly because of the cementing over of the banks of water bodies and hillsides (in the name of flood and mudslide prevention) and the destruction of mangroves, self-cleansing streams, storm-resisting swamps and flood-preventing forests.

The unfortunate reality is that every new government announces large infrastructure projects. Concretisation and infrastructure development are now synonymous with the rise from developing nation to superpower-in-waiting. The property sector in China – roads, bridges, railways, urban development and other cement-and-steel projects – accounted for a third of its economic expansion in 2017 and used almost half the world’s concrete. But, like the US, Japan, South Korea and every other country that “developed” before it, China is reaching the point where simply pouring concrete is doing more harm than good. In India, we are on the cusp of expanding our obsession with concrete. If we act quickly, we may be able to avoid more of the disastrous consequences of the overuse of concrete in city building.

Some cities are trying to repair the imbalance. Seoul removed highways along the Cheonggyecheon stream, Seattle replaced streets with permeable pavements, Zurich mandates all flat roofs in the city to be green surfaces.

The concept of ‘sponge cities’ is being adapted in the infrastructure of cities like Baicheng, Qian’an, Shanghai, Shenzhen, etc., in China with the objective of 80% of urban areas to absorb 70% of water by 2030. Instead of only impermeable concrete and asphalt, sponge cities need contiguous open green spaces, interconnected waterways, channels and ponds that can naturally detain and filter water and foster urban ecosystems, green roofs, porous roads and pavements and drainage systems that allow trickling of water into the ground and recycling.

Bengaluru is close to the tipping point. We need to re-engineer our use of concrete to save ourselves.

(The writer is a Bengaluru- based urban planner)