If Boston decided to set up a congestion zone, where would we put the boundaries? Boston could easily borrow from the successful models of both Stockholm and London. Stockholm is a city of islands, so it only needs camera gantries along bridges crossing its waterways. On its north side, Boston could replicate Stockholm by placing toll sensors on bridges over the Charles River from Cambridge, Charlestown, and East Boston.
The situation in Boston becomes more complicated to the west and the south, where drivers have myriad land entry points, such as along Soldiers Field Road, Commonwealth Avenue, Route 9, Columbus Avenue, Blue Hill Avenue, or Massachusetts Avenue.
Also needing to be accounted for are the highway exit ramps that dump cars off at the Prudential Center, South Station, and North Station. That is where London's example comes in handy; that city of 8 million people figured out how to ring its core with nearly 200 camera stations.
On the above map, I offer my own proposed boundaries for a congestion zone. My ring of about 20 primary entry points represents a desire not just to combat congestion downtown, but also in other areas where traffic has become horrible in recent years because of massive office development — most notably in the arc from Boston University down through the Longwood Medical Area and over to Northeastern University.
There are, of course, more streets that would need stations for those creative Boston drivers who would try to game the gantries, but I'll leave that up to city planners.