How Sweden cut traffic, from the Washington Post.
Traffic congestion sometimes seems like an utterly intractable problem. If a city suffering from gridlock tries to construct new roads to ease the pressure, traffic usually just increases to fill the extra space. Same thing when new bus and subway lines get built. Yet a few cities like Stockholm, London, and Singapore have taken a more market-oriented approach to congestion — treating it as an externality and essentially taxing it the way one might tax pollution.
The key word here is “sustained.” Earlier critics of congestion pricing worried that drivers would eventually get used to the tolls (Singapore, for one, adjusts its tolls to get the desired level of traffic flow, which sometimes means cranking prices up to painful levels). But Stockholm puts a flat $2.60 charge on all vehicles entering the city during peak hours and a $1.30 to $2 levy at other times throughout the day. And, so far, traffic appears to have stayed at reduced levels since the system came into effect in 2007 (the charge was passed into law after an earlier trial period in 2006).