With that said I do believe it should be dedicated ROW for the whole route, or at the very least built in a way to easily convert the short mixed-traffic segment into dedicated ROW later on.
This is where I am as well; I'll support this project if it meets that bar and oppose it otherwise. From now on I'm just going to call it a "tram" because I'm tired of trying to classify this project more specifically than that
So, to look more specifically at the corridor, my understanding is that the only really challenging segment to achieve this is 35E to Ann St; everything else has 2+ car lanes each way, sometimes even with parking. So from 35E to Ann we have 3 car lanes (1 each way + a two-way turn lane) plus parking on each side.
I guess there are some creative alternatives we could look into but in general I think we'd keep one car lane each way and so the big questions center on the impact on parking and the impact on left turns. With a center-running tramway, we could probably retain parking on one side, but left turns would have to be banned almost everywhere (except maybe at a few intersections with special signals). With trams in the outer lanes, we could keep left turns throughout the corridor but would have to remove parking entirely.
My preference is on center-running, first and foremost because it has the least interference from right turns/taxis/etc.
Given that parking is unmetered here, I don't see a really compelling case that we need two lanes of parking along the entire route. The demand just isn't high. I do think that keeping that space around on one side--using some combination of meters, a 15 min limit, a loading zone concept, etc--could be useful, so that's a point in favor of center-running.
As far as left turns go, it would be a culture change from "turn anywhere you want" to "here are the handful of places you can execute left turns", and we'd need left turn phases (separate from the tramway phases) at key intersections plus signage indicating additional spots where you can make a right then left (e.g., instead of a left from 7th onto Victoria, it would be a right onto Otto, then a left onto Victoria). But I think it could it could be workable. In terms of impact on traffic flow/throughput that would come from it (particularly if we have intersections with a green arrow but no left turn lane), it's a non-issue in this corridor IMO, since people on longer, higher-speed trips already have 35E and
Shepherd as alternatives.
Off topic, but I wonder if Siemens is developing or has developed a S70 model that can operate off-wire via batteries. I think it should be looked at for Riverview in which trains operate via overhead wires where they're already installed on the Blue and Green Line, and off-wire along West 7th. Less OCS to build and maintain, and in theory less cost.
I think the downsides of this--incompatible vehicles with the rest of the network, possibly higher maintenance costs associated with battery lifespan, negative environmental impact--are real, and the cost of installing catenary for 6ish miles is pretty negligible in the bigger context of the project.