What does Urban Congestion have to do with Mesh Networks?
Check out this very interesting article that suggests that placing mesh network nodes in cars is a far better way to implement congestion pricing than what has been tried so far.
The short paraphrase is that you can place mesh network nodes in cars and they can talk to an urban network to gain access and pay for access to the cngestion pricing zone.
And, here's the cool wrinkle , in doing that also get an urban wifi network 'for free'.
You have to read the whole article to follow the chain of reasoning but it's quite interesting.