Plastic roads: India’s radical plan to use its garbage to build hiways and biways

 

In India, roads made from shredded plastic are proving a popular solution to tackling waste and extreme weather
Jambulingam Street, Chennai, is a local legend. The tar road in the bustling Nungambakkam area has weathered a major flood, several monsoons, recurring heat waves and a steady stream of cars, trucks and auto rickshaws without showing the usual signs of wear and tear. Built in 2002, it has not developed the mosaic of cracks, potholes or craters that typically make their appearance after it rains. Holding the road together is an unremarkable material: a cheap, polymer glue made from shredded waste plastic... Plastic shopping bags, plastic packaging, bottles, jars and other food containers.


Jambulingam Street was one of India’s first plastic roads . The environmentally conscious approach to road construction was developed in India around 15 years ago in response to the growing problem of plastic litter. As time wore on, polymer roads proved to be surprisingly durable, winning support among scientists and policymakers in India as well as neighboring countries like Bhutan. “The plastic tar roads have not developed any potholes, rutting, raveling or edge flaw, even though these roads are more than four years of age,” observed an early performance report by India’s Central Pollution Control Board. Today, there are more than 21,000 miles of plastic road in India.  Most are rural roads, but a small number have also been built in cities such as Chennai and Mumbai.

Waste used to pave roads


Adding flexible materials to strengthen tar roads is not a new idea. Commercially made polymer-modified asphalts first became popular in the 1970s in Europe. Now, North America claims 35% of the global market. Modified asphalts are made from virgin polymers and sometimes crumb rubber (ground tires). They are highly versatile. They are also expensive. Polymer roads in the US are made with asphalt that comes pre-mixed with a  high grade polymer.


The plastic tar roads of India are a frugal invention, made with a discarded, low-grade polymer. Every kilometer of this kind of road uses the equivalent of 1 million plastic bags, saving around one ton of asphalt and costing roughly 8% less than a conventional road. Dr R Vasudevan, a chemistry professor and dean at the Thiagarajar College of Engineering in Madurai, came up with the idea through trial and error, sprinkling shredded plastic waste over hot gravel and coating the stones in a thin film of plastic. He then added the plastic-coated stones to molten tar, or asphalt. Plastic and tar bond well together because both are petroleum products. The process was patented in 2006. It will soon be used  on major roads and hiways and is expected to reduce construction costs  by 50%.


In India, plastic roads serve as a ready-made landfill for a certain kind of ubiquitous urban trash. Flimsy, single-use items like shopping bags and bubble packaging are the ideal raw material,  difficult to recycle, they are a menace, hogging space in garbage dumps, clogging city drains and even poisoning the air. Delhi’s air, in particular, has been called a “toxic pollutant punchbowl” partly due to contaminants from plastic-fueled street bonfires.


Last November, the Indian government announced that plastic roads would be the default method of construction for most city streets, part of a multibillion-dollar overhaul of the country’s roads and highways. Urban areas with more than 500,000 people are now required to construct roads using waste plastic. The project even has the blessing of India’s prime minister, Narendra Modi, who has made “Clean India” a kind of personal crusade.
India’s road upgrade is long overdue. A recent road safety report by the World Health Organization (WHO) found that 17% of the world’s traffic fatalities occur in India, with crumbling roads partly responsible for the high death toll. In 2014, potholes alone caused more than 3000 deaths.
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Dr R Vasudevan, a chemistry professor and dean at the Thiagarajar College of Engineering in Madurai.

The Delhi-Meerut Expressway, which is currently under construction, may use unsegregated trash from one of the capital’s overflowing landfills to build its base and embankments. In an interview with the Times of India, India’s roads minister Nitin Gadkari said: “Delhi will get rid of these mounds of trash and we will get the material for laying base with little expense.”

In the long run, sloughed off particles of plastic from the roads may affect the surrounding soil. But

in the short run, the bigger challenge for plastic roads is execution. Tamil Nadu was the first state in India to actively develop a cottage industry around shredded plastic. Most plastic shredders are women who buy subsidized shredding machines and sell their finished product for a small profit. Job creation for waste pickers and small entrepreneurs is an added benefit of the roads.

It's a win/win situation for a country with billions of tons of plastic waste and a great need for good low maintenance roads. Friends, Recycle, Recycle, Recycle!