Urban gridlock is so appalling a prospect to cities that many have now begun to enforce radical measures to 'cut' traffic. The formula that underpins all such efforts worldwide appears to be rather simple: keep cars off important city roads, at important times of the day, and for most part of the week.

Which is largely why 'congestion pricing' now appears to be the world's most preferred method of traffic discouragement. This mostly involves charging private cars a toll for entering key areas of a city, typically a 'city-centre' zone, or what urban planners call a CBD (central business district).

A few European cities have experimented with variations over the last decade. These include Oslo (Norway ), Stockholm (Sweden), Milan (Italy) and a clutch of cities across Britain, including London - where very high entry and parking charges in many city areas have caused much whingeing.

Yet, early verdicts on these attempts have been mixed. Many transport experts point to visible improvement, while critics argue that such coercion impinges on fundamental rights while limiting commerce and mobility, perhaps a principal reason the US is yet to implement similar proposals to decongest New York, Los Angeles and San Francisco.

China is a zealous convert to such strong-arm methods, with a slew of curbs being enforced in Beijing and Shanghai. But Beijing - home to 5 million vehicles, perpetual smog and the odd five-day traffic jam - is where the red lights are really flashing.

High-priced auctions for number plates, serious curbs on new registrations, restrictions on entry, and even systems to get some cars off the road temporarily (by allowing only even or odd license plates every alternate day) are all being tried out.

Asia was where it all began. Singapore has long been the gold standard for advocates of such coercion. Over three decades, the city-state's administrators have experimented with a host of measures to dissuade citizens from using and even owning cars.

These have included complex schemes to levy high parking charges and entry fees for cars entering CBD areas;fining single drivers - to encourage car-pooling for office commutes - and imposing steep taxes on car sales. It also includes regulating what Singapore calls a 'Vehicle Quota System' (which makes buying cars in Singapore an expensive proposition) and offering car owners incentives to get rid of old vehicles.

But such intense discouragement of private vehicle use can only succeed when cities are able to provide citizens another vital option - an extensively integrated and efficiently run public transport system. Singapore has one that's the envy of most. China has made huge investments in futuristic options in addition to rapidly building many. And Western Europe, where some of the world's most highly-rated pubic transport systems currently operate, plans upgrades for many existing arrangements.

Indian cities, though, can have no such luck for now. Notorious for their lack of integrated public transport options, most currently don't have a hope in traffic hell of forcing car users off key roads. Experts too discourage such measures.

Yash Sachdev, of Delhi-based transport consultancy RITES, points out that besides India's economic boom not countenancing such limiting of consumption, car use, not ownership, is what must be deterred. "For a country with relatively low vehicle ownership levels, we should not look to prevent people from buying them and seeking some independence. We should convince people to cut their preference to use them everyday, especially for work commutes, " he says. Restructuring tax options on vehicle use, he proposes, is one way to slowly test the water for any such future curbs.