The trial was initially due to have begun in June this year and last for 13 months, but the project was delayed due to heated political controversy and has now been shortened to just a half-year.
The test period is due to conclude at the end of July 2006, just six weeks before a referendum on whether to make the road tax permanent. The referendum will be held in connection with the September 2006 legislative elections.
During the trial, vehicles entering the inner city will have to pay 10, 15 or 20 kronor each time they pass a portal, with the amount of the toll depending on the time of day.
The highest amount will be charged during the morning and afternoon rush hours. There will however be no charge between 6:30 pm and 6:30 am, nor on weekends or holidays.
A maximum of 60 kronor will be charged per day.
The city of Stockholm will boost its public transport system in order to encourage people to leave their cars at home. In August this year and until the end of the trial period, some 200 buses will be added, as well as more frequent subway and commuter train traffic.
“The congestion on Stockholm’s streets costs society five to six billion kronor annually in the form of increased transport costs and reduced economic activity,” Environment Minister Lena Sommestad wrote in an article in daily Dagens Nyheter on Thursday presenting the project.
“If even just one of every 10 car trips were replaced by a trip with public transport, or were to take place outside of rush hour, the benefits of accessibility would be significant,” she wrote.
The government has previously said that the aim is to reduce traffic by 10 to 15 percent on the most overloaded roads, increase the average speed, and reduce emissions of health-endangering pollutants and carbon dioxide.
Buses, taxis, emergency vehicles, electric and hybrid cars will be among those exempted from the congestion charge.