I read the article you cite and the section in question is 4.5 blocks long. And the project included drainage, street lights on the far side away from the bike lane, paving the whole road, sidewalks, etc.
The Seattle city-wide average was $2mm/mile.
Very informative article, and it is completely different from what I thought I'd read based on your summary.
This [1] is a good overview of the general costs and trade-offs of various kinds of bike lanes in the US. Some benchmarks to get a feel for ballpark numbers [2] for US cities to start an analysis in your area. Basically in built-up areas in the US, options are pretty limited without overwhelming public demand for ejecting car drivers from an area in favor of pedestrian and cycling traffic.
I'm still looking for what it looks like when a city design favors pedestrian, cycling, e-assisted human-powered/assisted mechanisms (e-bikes, scooters, Segways, skateboards, skates, etc.) traffic, then on-call PRT-to-GRT-scale people/cargo/freight movers within neighborhood-scale distances in dense (40-50,000 people per sq km) developments, subways for inter-neighborhood connections, and vehicles are restricted to the city borders (kind of like restricting specific traffic at the network border) for large-scale commercial cargo and passenger transport.
I'd like to see a breakdown of where the capex and opex expenses come from for elevated and subterranean bike lanes. Building up and down seems currently a significant cost barrier.
Seems like they redid the whole street, sidewalks, street lamps, etc for those $12 million, and bike lane was just an excuse to do all that work. But yes, everything here is much more expensive than it should be. The "city overhead" itself was just above $1M.
As the articles goes on to point out, only that single section in the entire project will be that expensive, and that includes a lot of city upgrades that were otherwise needed and rolled into this (like new lighting, adding additional drainage, upgraded sidewalks, and new crosswalks).
To be honest the project sounds fantastic and I hope they keep at it. If they're able to roll in other upgrades at the same time, so much the better. The 12m figure is borderline clickbait (even if it is technically true).
[0] https://www.seattletimes.com/seattle-news/transportation/12-...