> I often wonder why new highways / lanes of highway don't get assessed in economic terms, but I suspect much of the day-to-day work would not be justifiable in such terms.

This is so frustrating. It feels like debate around a mile of bus lanes or rail can drag on forever, but spending billions of dollars on highways just happens.

People engage with roads at a purely emotional level. They don't want new highway lanes because the cost-benefit is strong and it will boost economic activity in their area. They want new lanes because they hate traffic with a fiery passion.