A traffic congestion charging system developed by IBM has cut queuing times in half on Stockholm streets during the morning commute, and has also reduced inner-city carbon dioxide emissions by 14 to 18 per cent.

The Stockholm Congestion Charging System has also reduced city traffic by 18 per cent, with the number of commuters on public transport rising by about 7 per cent, or 60,000 passengers per day, according to a study by the Stockholm City Traffic authorities.

The study also finds that the number of “green,” tax-exempt vehicles has almost tripled, with the congestion charging system the most influential factor in motorists’ decision to choose less-polluting cars.

During 2008, the congestion charging system handled about 82 million vehicle passages, with an accuracy exceeding 99.99 per cent, according to IBM. The system was rolled out in August 2007, following a successful pilot.

“It is quite clear that the positive effects of the congestion charging system are continuing,” said Ulla Hamilton, vice mayor of Stockholm. “Reducing traffic volumes, decreasing CO2 emissions and improving accessibility is bringing significant benefits to the city, its visitors, and residents, and has been a factor in Stockholm being awarded European Green Capital for 2010. It is also satisfying to see that the retail business in the city has not suffered as a result of the congestion charging system.”

The congestion charge is a national tax, with net income expected to be $84 million (US) in 2010, returned to the Stockholm region for investment in traffic infrastructure.

“Intelligent transportation systems like the Stockholm solution are key to effective traffic management and sustainable cities.” said Jamie Houghton, IBM’s global leader for intelligent transport systems. “The Stockholm scheme will continue to be a major influence on many other cities considering managing the challenging urban development without incurring the costs of building new roads.”

As the world becomes more urbanised — with 70 per cent of people expected to live in cities by 2050 — municipalities are struggling to keep pace with increased traffic and congestion problems accompanying urban growth. A report from IBM indicates that transport has emerged as an urgent priority for municipal planners who need to improve traffic flow to promote cleaner, less congested cities.

The Stockholm system is the largest of its kind in Europe, with 18 barrier-free control points around the inner city equipped with cameras to identify vehicles around a 24-square-kilometre area. IBM is also working with London, Singapore and Brisbane to address traffic management and congestion challenges.

• IBM: Swelling cities need smarter traffic systems