Why aren’t Indian roads as good as the ones in the US?


There is a reason for this that is rooted in Civil Engineering. Thomas Tharu, who is one of the finest engineers I know, showed me a monograph he’d written about this topic a while back. It was a fascinating scientific insight into a problem that most of us dismiss with a non-scientific explanation like corruption.

(Asphalt) roads around the world have pretty much the same construction. There is a layer of gravel (I’ve heard it called ‘jelly’ in Chennai and possibly the rest of India too) and on top of that, there’s asphalt – a concrete mixture with a substantial bituminous / tar component. The asphalt is mildly permeable and can deform to bear very heavy loads; the gravel layer underneath, and the basic soil itself, provide the structural strength for the road to ‘re-form’ after plastic deformation by a truck or bus that passes over it.

If you observe the degradation of Indian roads carefully, you will find one remarkably consistent property: roads are not destroyed during regular use. They are destroyed during rains. This fact alone should have been sufficient to tell you that it is not petty corruption, or so-called “bad quality roading”, that is the explanation for our nasty roads. Water has something to do with it, too.

What, exactly? Well, when a road floods, i.e. it is covered with water for extended periods of time, water seeps through the asphalt layer into the gravel. And here is where water gets particularly destructive: it lubricates the gravel, allowing the underlying rocks to move against one another. What results from this is that the normal function of the gravel – which is to provide foundational support to the plasticity of the overlaid asphalt – is degraded substantially. When the asphalt deforms due to load, the gravel underneath also deforms. This results in potholes, which grow by successive applications of the same process into the horrid broken-down roads we see so often. You can see, in the photograph below, that the asphalt has not only deformed but has also been completely eroded in some places due to water.

So why does this not happen in other countries? For a very simple reason: well-built roads, all over the world, will never have water stagnating on top of them. One reason is purely geographic: the intensity of rainfall in India is often much, much more than in other countries, and so there is a huge chance for flooding. The second reason is technical. There are two mechanisms to prevent water stagnation in a well-constructed road. The first is camber: a well-made road peaks at the center, and slopes on the sides, so that the water drains off to the sides. And most Indian roads do have a camber. But the second mechanism is drainage – storm-water drains – that ensure that take all the water that is drained to the sides of the road by the camber, and carry it all away to a water body.

In India, we simply don’t have the space for drainage in the vast majority of our city roads. A typical road in a city runs between tightly-built-up space, a wall on both sides, and has just enough space for two lanes of traffic going in opposite directions. It is simply not feasible, physically, to have a storm-water drain or even a footpath on the sides. However well the road is constructed, without drainage, it will suffer during a monsoon. Land acquisition is the long-term answer to this problem, but people in India are dead-set against the Government acquiring their land for public works, not least because there is a huge discrepancy in the ‘black’ value of land and what the Government can pay.

One more factor. The next time you are on a major road, look for the drainage holes from the road to under the footpath. Most often, you’ll find it covered or blocked with litter, impeding water flow. That plastic bag you throw on a road will soon become a pothole.

There is one very simple way to reduce the damage to flooded roads, and that is to limit the flow of traffic during rains. If you observe which roads get ruined the most during rains, you’ll see it is the ones on bus routes. While any kind of load leads to plastic deformation, the heaviest loads are the ones that do the most damage. Cutting down bus and lorry traffic during monsoons is the surest way to prevent degradation of roads. But that’s a political matter and disproportionately affects the poor, who do not have the luxury of ‘working from home’ when the monsoons arrive.

In Tamil Nadu, there are two things that have contributed to roads having a somewhat longer life than in the rest of India. First, rain-water harvesting was made compulsory about a decade ago, and since then, there is a lot less water draining onto the roads. Second, it’s very common to declare holidays for schools, colleges and Government establishments when it rains, cutting down on traffic.

But the bottom line is that the bad roads in India are not the main responsibility of the people who lay the roads. If you want better roads, you need more people giving up land so that roads can be widened with drainage on the sides; and you need people to agree to use the roads less (and use public transportation less) during rainy seasons. These are political problems. And in a country with a billion people who each have a vote, political problems require consensus, goodwill and leadership to solve. That’s what we should be focusing on.