Even by the standards of a highly-ordered country, the traffic on Singapore's roads flows with an almost eerie smoothness. At the height of the city-state's rush hour, cars glide at a steady pace along the expressways, without traffic jams.
Credit for an achievement that can only be the envy of motorists in Paris, London and Los Angeles, goes to the world's most sophisticated and oldest system of charging for road use, in place since 1975.
Motorists are charged every time they pass one of 45 gantries on expressways and roads in Singapore's urban centre at busy times.
Prices are adjusted every three months to keep traffic flowing at an optimum speed which allows the maximum number of vehicles to use the road. If flow is too slow, prices are raised. If it is too fast, prices are lowered. It is the kind of scheme that is set to become more and more widespread after three decades when Singapore had a quasi-monopoly on such practices.
The UK is expected on Thursday to reiterate its commitment to becoming the world's largest country to switch to charging for distance driven, away from a tax on fuel consumption.
London is proposing to charge drivers variable fees for all road use, depending on time of day and location, in a scheme that would take 10 to 15 years to introduce.
Although many countries have long had tolls for bridges, tunnels or motorways that were especially costly to build, an increasing number are now also looking at more systematic charges to reduce congestion, raise revenue or encourage other modes of transport.
The UK has already shown itself to be a pioneer in this area, when London introduced one of the biggest city congestion-charging schemes in February 2003.
Austria and Germany have started charging trucks to use their motorways, a practice extended by Switzerland to the entire road Network. Britain is also due to introduce a national road-charging system for trucks in 2008.
The US state of Oregon is also considering a charging scheme, while some cities in Norway charge vehicles to enter city centres.
Schemes still face considerable practical problems: the UK, for instance, will have to fit road-pricing equipment to more than 30m vehicles, against only about 700,000 in Singapore. Substantial political challenges also loom as when voters in Edinburgh in February rejected plans for a congestion charge on vehicles entering the Scottish capital.
Yet charging for road use also has potential to tackle some of the world's toughest transport challenges. Growing traffic volumes and the increasing fuel-efficiency of engines lie at the heart of the challenge for many countries.
Growing efficiency has made fuel taxation the traditional means of charging for road use less effective because vehicles use less fuel per kilometre driven. That, together with falling car production costs, has made driving cheaper as more environmentally-friendly alternatives, such as rail, become more expensive.
Different road-pricing schemes target different aspects of the problem.
Chin Kian Keong, chief engineer for transportation at Singapore's Land Transport Authority, says Singapore's scheme was not introduced primarily to raise revenue.
“We always position our road-pricing system as a congestion or traffic management tool not as a tool to get revenue,” he says. “That principle has remained until today. Revenue was not a consideration.”
The state of Oregon, however, has said it is looking at road-pricing mainly because more efficient engines are reducing the fuel tax revenues it needs to build and maintain roads. Road-pricing revenues would more accurately reflect the damage done to its roads by increasing numbers of cars.
Meanwhile, Switzerland introduced its charging scheme for lorries in an effort to reduce the number of trans-Alpine truck journeys and to encourage a switch to rail.
Some two-thirds of therevenue pays for investments in Switzerland's rail network.
However, the most powerful argument for road-pricing may be that it is one of the few anti-congestion measures that can produce almost instant results.
According to Kurt Moll, head of freight and traffic at Switzerland's Federal Transport Office, truck trips have fallen by 10 per cent since Switzerland introduced its charge in 2001.
Traffic entering central London when its £5 congestion charge was in force fell 15 per cent during the charge's first year. Time lost to traffic hold-ups fell by 30 per cent in the period.
In Singapore, the simple switch from a paper-based system using toll booths to an electronic system where prices could be varied reduced traffic at the busiest times by 15 per cent in the first year.
As the world's roads grow more crowded, more and more governments may well conclude it is worth taking the risks necessary to achieve such gains.
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