## Road Widening is NOT the solution

The other day, walking down Dr. Rajkumar Road in Rajajinagar, I saw several signboards on the road, on shopfronts, on buildings, etc. protesting against plans for widening the road. Apparently they want to widen the road and thus want to demolish shops, parts of houses, etc. Looking outside my own apartment building the other day, I saw some numbers written on the compound wall. Digging deeper, I figured that they want to widen the road I live on and hence want to claim part of the apartment land.

Now, the logic behind road widening is not hard to understand – due to increase in traffic, we need more capacity on the roads and hence increasing their width results in increased capacity in terms of vehicles per unit time and so it is a good thing . However, before going headlong into road widening and land acquisition for the purpose, road architecture in the city needs to be studied carefully.

There are two primary reasons why trafffic bottlenecks happen. The more common reason at least in western nations is road capacity. Roads just don’t have the capacity to take more than a certain number of cars per hour and so when more cars want to go that way, it results in pile-ups. The other problem, which I think is more common in India is intersections.

It is going to be a tough problem to model but we should split up roads into segments – one segment for each intersection it is part of, and one segment for each segment between intersections (ok it sounds complicated but I hope you get it). And then, analyzing capacities for these different segments, my hypothesis is that on an average, “capacity” of each intersection is lower than the capacity of road segments between intersections.

Now how does one calculate capacity of intersections? Assume an intersection with traffc coming from all four directions. Suppose traffic approaching the intersection from north sees green light for fifteen seconds a minute. And in each fifteen second interval, 25 cars manage to make it past the intersection. So the capacity of this intersection in this direction becomes 25 cars per minute. I hope you get the drift.

I’m sure there will be some transportation engineers who will have done surveys for this but I don’t have data but I strongly believe that the bigger bottleneck in terms of urban transport infrastructure is intersections rather than road width. Hence widening a road will be of no use unless flyovers/underpasses are built across ALL intersections it goes through (and also through judicious use of road divider). However, looking at the density of our cities, it is likely to prove extremely expensive to get land for the widened roads, flyovers etc.

I don’t see private vehicle transportation as a viable solution for most Indian cities. Existing road space per square kilometer is way too small, and occupation way too dense for it to be profitable to keep widening roads. The faster we invest in rapid public transport systems, the better! I’m sure the costs borne in that direction will be significantly lower than to provide infrastructure to citizens to use their own vehicles.