Commuting trends: transit vs driving vs ...

[tomh009]

I think it is still too early for me to understand the question, but here is an attempt.

The costs (2016) are broken down this way:
Winter maintenance = $4,322 per lane km or $1.22 per m2 (assuming 3.65m lane width)
Total maintenance cost = $19,138 per lane km or $5.24 per m2 (assuming 3.65m lane width)
Total cost (including amortization, disposal, capital, maintenance) = $32,568 per lane km or $8.92 per m2 (assuming 3.65m lane width)
(...)
Each year, the total non-maintenance costs of the original road is $26,860.
Each year, the total non-maintenance costs of the narrowed road is $26,124.
A difference of $736.

Right.  But what is the incremental cost of rebuilding the street as a narrower one?  That's the up-front cost, which would eventually be paid back in maintenance savings.