The reason we don't have much transit is because our transit is expensive.
But the reason that transit is expensive here is that it is planned with the fundamental assumption that drivers must not be inconvenienced. Tunnelling is expensive and wildly increases uncertainty and cost, but why are we tunnelling? The only things in the centre that the Green Line fundamentally can't cross at grade are the CP Rail and the river. Everything else is a choice. The Beltline portion of tunnelling was largely to avoid crossing Macleod at grade and inconveniencing drivers. Running downtown at grade could make east-west traffic a little slower, but not a lot. Instead of taking two lanes from 11th avenue and First street, we're spending a billion dollars. If the situation was reversed and the train was there already, would we spend a billion dollars to add two lanes to these roads? There should be the same answer to both questions.
North-south and east-west LRT lines cross at grade in downtown Portland (it's even one 1970s high-floor line and one current low-floor line like we have), so it should be possible to do that here as well, although our east-west corridor has higher train volumes, and eventually there will need to be a tunnel downtown somewhere.
There's a great saying in German, Organisation vor Elektronik vor Beton -- organization before electronics before concrete. That is, the first and cheapest changes involve optimizing your organization and operating; the second best is optimizing your signals and so on, and only once those have been exhausted should you build new infrastructure. We've taken the reverse tack here, very much at our cost.
It's not that the portion of the Green Line project that serves transit users is expensive and risky; it's the portion that serves drivers.
