What always seems to get lost in the discussion about Portland's streetcar system is that not all of it runs through dense, urban, massively successful redevelopment like South Waterfront or Pearl District, or already existing dense neighborhoods such as Downtown and Portland State; some of it runs through leafy, almost suburban neighborhoods (now note, these aren't Sunbelt-suburban, more like dense suburbs that developed around turn of the century transit lines).
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Like here, at NW Northrup & 21st Ave:
It seems to fit in rather well with the streetscape, too. And whenever I rode it, the streetcar never had problems with car traffic, other than a lack of signal pre-emption, which could be fixed. Every time I rode, too, the cars were all 60-90% full, no matter whether it was 11AM or 9PM.
Now, noted, this was close to Nob hill, which is one of the trendier neighborhoods, so that could've accounted for some of the traffic, but ridership seemed a mix of young and old, tourist and natives.
I think neighborhoods like this could be something to aim for in Austin, which has lots more leafy suburbs with slightly built up commercial areas, than old industrial districts to totally renovate with art galleries and trendy lofts. In fact, the area reminds me most of Austin's Hyde Park, which was at one time a streetcar suburb, and it seems would benefit from reestablishment of a transit line.