technology waste

Are plastic roads a waste solution?

What to do with all the world’s plastic waste? More and more things, from construction materials to clothes, are made from plastic – with no obvious way to recycle them. Of what can be recycled, far more is being created than can be economically collected and processed. Other than burn it or dump it in landfill, what else can we do?

How about melting it and layering it into our roads?

That’s a plastic waste ‘solution’ that was first developed in India in 2001, and it was trialled over the next decade. The results were so successful that in 2017 the government mandated that new roads in India should incorporate plastic. There are now tens of thousands of miles of plastic roads across the country, and the idea has spread elsewhere. There are plastic roads in several places in the UK, and they can be found in Spain, Indonesia, South Africa, Estonia, Australia and many other places. The first in America were installed on Staten Island a couple of months ago.

The way it works is that waste plastic is shredded and melted into the bitumen mix. There are different companies with different formulas, but in India it’s around a ton of plastic per mile. This keeps the waste out of landfill, and saves carbon emissions by replacing around 10% of the bitumen. It’s cheaper too. A tonne of bitumen costs almost three times more than a tonne of waste plastic, so there’s a modest saving per mile.

The really compelling bit for decision makers is that plastic roads are better. Studies show significantly less wear and tear compared to traditional roads. That’s because the plastic gives the road surface just a bit of flexibility, reducing the cracking that inevitably leads to potholes. Water run-off is also better, and water getting in the cracks of the asphalt is another factor in roads breaking down. So plastic roads need less maintenance, and last longer. That dramatically multiplies the emissions savings, as road-building is an energy and resource intensive business.

If you can build better roads, that are cheaper and that help to tackle a waste problem, it’s easy to see why this idea has got some serious backing. In Britain, the government recently ear-marked £23 million of public funds towards plastic roads.

On the other hand, among the problems with plastic is that it is non-biodegradeable and essentially lasts forever in the environment. That’s true whether it’s in the form of a bottle, or in the form of a road. So plastic roads are potentially a solution to overloaded landfill. They’re not ultimately a solution to plastic pollution itself. The plastic has still ended up in the environment, just in the form of a road. When that road is eventually taken up, it will be in the rubble, where it will presumably remain for all time. “Putting the plastics in roads does not make plastics disappear,” writes the environmental activist Nityanand Jayaraman in a critique of the idea. “They are merely hiding.”

To anticipate a question – no, it apparently doesn’t shed microplastics. That’s because the plastic is melted and bound into the mix, so it’s not in a brittle state. At least, that’s according to independent studies commissioned by MacRebur, the leading firm in the UK that’s doing it.

I can see how plastic roads look like a solution from the perspective of local councils, but the problem with plastic isn’t just the logistical question of how to process it all. It is by nature non-biodegradeable and can’t be reabsorbed into the earth’s natural cycles. It fundamentally doesn’t belong, and so it accumulates. Finding ingenious new uses for waste plastic doesn’t address the basic problem that once plastic has been made, it never goes away. We already have plastic on Mount Everest and in the Mariana Trench. We have microplastics in our food and in our bodies. Surely the solution has to be to reduce the use of plastics, and eventually eliminate its non-biodegradeable forms altogether?

Another reason to be sceptical is the small matter of who is investing in plastic roads as a solution. There are some familiar faces. The first plastic road in Pakistan was a collaboration with Coca Cola, the world’s biggest source of discarded plastic bottles. You can see why they would want to champion it, because they can claim the environmental benefits without any change to their packaging and their business.

Plastic roads would also benefit the oil and gas companies, who have been increasingly keen to diversify into plastics as a way of hedging against any reduction in fossil fuel use. So it’s no surprise to find that Total is one of the three partners behind PlasticRoad, a slightly different approach in which the entire road is made from plastic. Expanding our use of plastic in road construction would help to lock in future business for the oil and gas companies.

So, what to make of plastic roads? I can’t quite make up my mind on this one. I think some of the people promoting them have their hearts in the right place. I respect the fact that it’s solving a pollution problem in some places, and that it makes better roads. But I’m not convinced that mass produced plastic should have a long term future, and so ultimately, neither should plastic roads.

1 comment

  1. It’s worth bearing in mind that the tar in the tarmac is similarly non-biodegradable; in fact plastics are in many ways similar to tar, just with longer-chain molecules. So we should be consistent in our scrutiny vs acceptance of both the tarmac and the plastic locked within it. If it’s ok to recycle tarmac in given ways, then it may be similarly ok in some circumstances to recycle plastic-loaded tarmac. If it reduces the overall market for extracting oil from the ground (e.g. by making the tar stretch further and last longer) then it could even be a net positive thing. Or am I missing something?

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