A big debate on urban transport policy has been triggered by the decision of the state government of Delhi to restrict automobile usage according to the licence plate number. The plan is to significantly reduce vehicular traffic by allowing odd and even numbers to ply the roads on alternate days. Given the city’s atrocious air quality, something drastic needs to be done. The problem is that this particular policy has been tried in other countries for years with poor results except for short periods. The danger is that a focus on implementing this policy will divert attention from more serious solutions. 

The idea of using the licence plate number to ration road space is not new. It was used by the Chinese authorities during the Beijing Olympics to improve air quality and is said to have had some impact. A more permanent restriction called Hoy No Circula (No Circulating Day) was introduced in Mexico City in 1989 that banned drivers from using their car once a week based on the licence plate number. Different versions were subsequently adopted by other Latin American cities like Bogota and Sao Paulo. Again, there were clear short-term benefits. Mexico City, for instance, saw a 20% reduction in vehicular traffic in the first few months. 

Unfortunately, the longer-term outcomes were not so encouraging. A study of air quality impact published in 2007 by Lucas Davis of the University of Michigan concluded: “Across pollutants and specifications there is no evidence that the program has improved air quality. The policy has caused a relative increase in air pollution during weekends and weekday hours when the restrictions are not in place, but there is no evidence of an absolute improvement in air quality during any period of the week for any pollutant.” 

It turns out that people begin to game the system once it’s permanent. Mexico City residents began to buy extra cars with convenient number plates. In fact, they slowed down the purchase of new cars and began to buy old, inefficient cars from the rest of the country. This actually made things worse. Moreover, the shift in the mode of transportation was from cars to taxis rather than to metro trains. Thus, the taxis made more money but air quality did not improve. After two months of implementation, petrol sales went up. Based on these findings, a technical study commissioned by New York City argued against introducing such a system in 2007. 

The Delhi government has announced that it will do a trial run from the beginning of January 2016. My guess is that the trial will show some positive results that can be misleading as it will provide no indication of how Delhiites will adjust their behaviour to a permanent imposition. It is almost certain that the rich will buy multiple cars to get around the restrictions and the extra idle cars will lead to a parking nightmare in residential neighbourhoods. An additional problem will soon arise over what to do with cars from other states. If the same restriction is not placed on them, Delhiites will just register cars in other states. However, the imposition of the restriction on non-Delhi cars will cause problems for visitors who genuinely happen to be visiting the city for a short duration. If not sensibly handled, it will spiral into an inter-state spat. 

A key condition for the success of road rationing is that alternatives are easily available. The building of Delhi Metro has certainly improved public transport in the city and buses are now much better than the old DTC (Delhi Transport Corporation) clunkers. However, the frequency and network are still far from adequate and, on many routes, the services are running at full capacity. There is an even bigger problem that is almost never discussed—the appalling state of pedestrian infrastructure. All public transport systems are based on the last and first mile being walked. This is not only about sidewalks but also crossings, street-lighting, cleanliness, the removal of feral animals and so on. Safety for women is a particular concern. Having studied public transport systems around the world, I can say that this is by far the most serious bottleneck to the use of public transport in Delhi (and most other Indian cities).

Meanwhile, the Delhi government may consider other alternatives. Singapore, for instance, uses a system of auctioned permits and electronic road pricing. Thus, the restriction is based on price rather than on rationing. Cars are charged as they drive around the city and the pricing varies on location and time of day. Such a system will require some upfront investment in technology but the outcome will be vastly better and give car users a lot more flexibility. Perhaps Delhi could even leapfrog into a more advanced GPS (global positioning system)-based system. 

Delhi clearly needs a solution but it makes no sense to rush into a system with a dubious international record. The danger is that it will use up a lot of resources and energy that could be better aimed at other solutions—such as fixing pedestrian networks.