Tag: bottlenecks

My tryst with Kannada media

So about a month or so back, I wrote up an essay on why the much-maligned TenderSURE project is a right step in the development of Bangalore, and why the Chief Minister’s comments on the issue were misguided and wrong.

Having written it, considering it worthy of a better forum than NED, I shared it with my Takshashila colleagues. They opined that is should get published in a Kannada newspaper, and Varun Shenoy duly translated the piece into Kannada. And then the story began.

We sent it to PrajaVani (which has published several other Op-Eds from other Takshashila people), but they summarily rejected this without giving reasons. We then sent it to UdayaVani, reaching it after passing some hoops, but then they raised some questions with the content, the answers to which had been made quite clear within the text.

I think Mint has spoilt me, in that I assume that it’s okay to write geeky stuff and have it accepted for publication. Rather, it is possible that they’ve recruited me so that they can further bolster their geek quotient. Last week, for example, I sent a piece on Fractional Brownian Motion, and it got published. A couple of years back I’d sent a formula with Tchebyshev’s inequality to be included in a piece on sampling, and they had published that too.

When translating my piece, Varun thought it was too geeky and technical, and he made an attempt to tone it down during his translation. And the translation wasn’t easy – for we had to find Kannada equivalents for some technical terms that I’d used. In some cases, Varun expertly found terms. In others, we simply toned it down.

Having toned down the piece and made an effort to make it “accessible”, UdayaVani’s response was a bit of a dampener for us – and it resulted in a severe bout of NED. And so we sat on the piece. And continued to put NED.

Finally, Varun got out of it and published it on the Takshashila blog (!!). The original piece I’d written is here:

A feature of Bangalore traffic, given the nature of the road network, is that bottlenecks are usually at the intersections, and not at the roads. As a consequence, irrespective of how much we widen the roads, the intersections will continue to constrain the flow of traffic in the city. In other words, making roads narrower will not have a material impact on the throughput of traffic in the city.

And Varun’s translation is here:

(Update: I tried to extract Varun’s piece here but it’s not rendering properly, so please click through and read on the Logos blog)

Read the whole thing, whichever piece you can understand. I think we are on to something here.

And on that note, it might make sense to do a more rigorous network-level analysis of Bangalore’s roads. Designing the graph is simple – each intersection (however small it might be) is a node, each “road segment” is an edge. The graph is both directed (to take care of one-ways) and weighted (to indicate width of roads).

We’ll need data on flows, though. If we can get comprehensive data of origin and destination of a large number of people, we should be able to impute flows in each segment based on that.

And then we can rigorously test the hypothesis (I admit that it’s still only a hypothesis) that bottlenecks on Bangalore’s roads are intersections and not roads.

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.

Strategic Food Attack at Functions

While standing in line waiting rather impatiently for my dinner at Monkee’s engagement today, I was thinking of strategies that one can employ in order to get one’s food quickly in places where there are long lines. I’d faced the same question a couple of weeks back at Sharadha’s wedding, where again the lines were insanely long. On both occasions, I think I managed to figure out reasonable solutions.

The thing with most guests at functions like these is that they tend to approach the food in linear fashion. They start from one end and go through the whole line taking little bits of everything on the menu. Most people I know, especially from the older generation, don’t go back for a second helping. And so this means that they need to get everything the first time round.

The key to cracking the puzzle is to approach things in a non-linear fashion, as I realized at both Monkee’s and Sharadha’s functions. Like for example, today I managed to break down the queue into various sub-queues and with quick mental analysis understood the bottlenecks, and decided my diet for the night based on that.

For example, today I noticed that the main queue was for one table where you got the plates, pakodas, thair vade, jalebi and some salads. These things had all been arranged around a table which seemed non-intuitive to a lot of people because of which the crowd was heavy. And I realized that just to pick off the plate from the stack and scoot off, I could break the line without being impolite.

Next, analyzing the main course queues, I realized that one main line was at the dosa counter, and decided to forego it in the interests of getting my food quickly. Again I quickly ran this optimization algorithm in my head which told me that it was best to have rotis (involved a small wait) and curries in the first round and then rice in the second. It worked beautifully, and I had a hearty dinner without ever standing in line!

At Sharadha’s wedding too I had managed to spot and exploit arbitrage opportunities. For example, I realized that people never stood in queues to get second helpings, and that I could peacefully get around the line by taking the plate from the hardly-crowded salad counter and then going to the main line looking like I was going for second helpings.

The key at buffets is to keep your eyes and ears (yeah, I managed to “spot” that spoons had arrived by hearing their clanging) open to any sort of arbitrage opportunities, and once spotted to ruthlessly exploit them. And you need to be a little RG. If you try to take along too many people when you are implementing such plans, it will be self-defeating and your returns diminish.

And if you find yourself at a buffet which has lots of financial traders, I really pity you.

Why Inclusiveness Matters

I want to take examples of two situations from traffic engineering to demonstrate why inclusion is important, and it is critical that everyone be “taken along” in any grand plan. The usual arguments for inclusion that you find from proponents of schemes such as the NREGS is that if you don’t include, people will riot and cause harm to others. What I want to show is that even if people have non-violent non-disruptive benign intentions, non-inclusion can lead to disaster for the society at large.

My current workplace is at Embassy Golf Links on Inner Ring Road (between Koramangala and Domlur). Approaching from the Koramangala side, one needs to take a u-turn at the old airport road in order to access the complex. And the story of my first two weeks in office has been that it takes 25 minutes to get from home to the other side of the road, and another 25 minutes to take the U-turn and get on the right side of the road. Some quick and dirty analysis of the bottlenecks tells me that the problem is not with the design of the Airport Road flyover (as many would suspect). It’s much simpler.

A common error in traffic planning is that the planners fail to take into account pedestrians. Pedestrians are not counted as “traffic” and are assumed to somehow get on with their lives while the cars and bikes zip by or crawl in the traffic. Because of this, not enough facilities are made for pedestrians – for them to walk, for them to cross the road, etc. thus forcing jaywalking.

If you look at the area on inner ring road around the airport road flyover, you will notice that the biggest problem is pedestrians. No, pedestrians are not a problem, the problem is lack of facilities for pedestrians which forces them  to jaywalk. So every handful of metres on the road, you’ll notice a handful of pedestrians holding across their arms and trying to wade through the traffic, thus significantly slowing down the traffic. It is because these pedestrians were not included in the original traffic plan that the whole system has failed. So we see that even though the pedestrians mean no harm to others, they are inadvertently causing harm to society at large. And it’s still not too late – a couple of overhead crossing bridges can be installed which should make life peaceful again.

Coming to the second issue – public transport. Last monday the Vijaya Karnataka had done a feature on the Bangalore Metropolitan Transport Corporation (BMTC) and had carried out a scathing attack for not doing enough for the common man. I just skimmed through the article and the central idea was that public transport is essentially meant for the poor and downtrodden who can’t access any other kind of transport, and so the BMTC’s focus on higher-end buses (Vajra and Suvarna) is doing a lot of harm for the mango person who still has to go in highly crowded buses.

What the writer of the article fails to notice, or chooses not to notice, is the substitution effect. Give a poor man a comfortable bus, and you will take one cycle or scooter off the road. Give the rich man a seat in a comfortable bus, and you will take a car off the road. And taking cars off the road means that everyone now gets to travel faster – both the remaining cars as well as the buses – carrying both the rich and poor. Thus it is probably more pareto-optimal to put an extra high-end bus on the road rather than an ordinary bus (though of course we need enough of the latter).

One major bane of public transport planning in India (and abroad) has been the assumption that public transport is for the poor, and excluding the rich out of the equation. Not finding decent public transport option, the rich has thus gravitated to using one-passenger cars which have had a disastrous effect on traffic in general. And it is only now that cities are taking an inclusive approach and planning public transport for everyone, and you see various cities putting in place high-end buses. Given the secular growth in cities and in traffic, it is probably not possible for us to do an analysis as to what would’ve happened without high-end buses, but I’m sure we are better off with these rather than without these.

So the moral of the story is that when you are planning (regardless of whether you are the government, or a corporate, or the head of a family), you will need to take into account all possible stakeholders, including those outside the system being designed. Only then will the design be efficient.