"Despite proven success, the idea of using congestion charging to reduce traffic is not widespread, due to political doubts regarding social and economic justice, rather than issues of traffic design or traffic stream engineering.
...Investigation of an ancient traffic custom may shed some light on the problem. In ancient Roman times, public roads were considered "Res Publica", or in the "public domain", the common property of all. A solution to the congestion charges conflict may be found in an ancient law related to a nucleus congestion problem -- a conflict between two boats or camels that had to pass through a narrow passage wide enough for only one traveler to pass. Understanding the solution to the nucleus conflict between two opposing interests may be the key to a multi-vehicle conflict that occurs under congestive conditions."
Thanks to David Gest