[kasey_junk]

You sort of can’t directly calculate externalities. That’s what makes them externalities.

The common answer is to not calculate it but to add a carbon tax. If you make gas more expensive, road taxes higher and non-renewable energy higher cost, the market actors will change their behavior.

As for the infrastructure cost, you pay that in either case and it’s more efficiently built the denser things are.

[wait-a-minute]

Or you can target the largest sources of pollution without punishing regular working people via carbon taxation.

[kasey_junk]

This isn’t a bottleneck style problem where removing the worst thing reorders the thing underneath it. We need to start targeting all of the inefficiencies and carbon emitters. The suburbs are worse for the environment plain & simple so we need to improve on that.