Saturday, December 05, 2015

Banning Odd and Even Numbered Vehicles in Delhi for Better Air Quality

Lets be clear that this is a good idea, but an implementation nightmare, if checks and alternate options are not put in place by January 1st, 2016.

When we talk of emissions from road transport, we are looking at three contributing factors

1. number of vehicles (NV)
2. number of vehicle km traveled (in a day or year) (VKT)
3. emission rates per vehicle (EF)

The odd/even rule comes under (1) - cutting the number of vehicles on the road. You cut 50% of the vehicles, you get 50% of reduction in the emissions, assuming that the other two parameters are not changing. But, it is likely that (2) will go up. On a day odd car is banned, the even car could be doing double the number of km, which could bring the reductions back to zero. The best seal proof option is (3). You introduce better fuel, the overall fleet emission rate improves, and achieve complimenting emission and pollution reductions.

This is not to say that technology is the only or the main option. We do need a change in the on-road travel behavior. We want sustained emission and pollution reductions in the city. We need people to not use their car or motorcycle and instead walk, cycle, or go by bus - assuming that all these facilities are in place, to accommodate the transition. 

So, in numbers

50% reduction in NV, 0% change in VKT, 0% change in EF = 50% reduction in emissions
50% reduction in NV, 100% increase in VKT, 0% change EF = 0% change in emissions
50% reduction in NV, 0% change in VKT, 50% reduction in EF = 75% reduction in emissions
50% reduction in NV, 50% reduction in VKT, 50% reduction in EF = 87.5% reduction in emissions

I hope that this rule applies to all the vehicles - cars, motorcycles, light duty trucks, and heavy duty trucks. Otherwise, exceptions (I am sure there will be) will only cut into any possible benefits.


amit said...


Thanks for this post. Of course you are spot on in your observations and I fully agree with the outcomes as envisaged by you. The odd /even number scheme is just barking up the wrong tree.

Please can you help me read the graph posted in this article. What do the values on X & Y axes represent?

Many thanks and please keep up this enlightening work.

Sarath Guttikunda said...

Thank you.

A new infograph, with back of the envelope calculations on this rule