There is interest in exploring cycletrack opportunities where we have excess road capacity in Portland. There aren't many locations where this is easy to do persay, but jumping off from Ronald Tamse's (Dutch Engineer) recent presentation, it's not a very far leap to find the right spots where there's space available.
In order to transition back from a cycletrack into a spot where capacity is constrained takes care. You can maintain adequate capacity when making the transition if the signal timing is combined with geometric design elements like we produced on NE 12th Avenue. To this end, I think New York City is onto something for making a cycletrack work well at intersections. They take care to produce a "Mixing zone" at right turn opportunities that blend the facility in with the traffic. The diagram on the right isn't for the heaviest right turn traffic, but it seems to offer promise for retaining the auto capacity while providing opportunities for finding the right match.
The research conducted by Portland State University about our SW Broadway cycletrack suggests that its an application that will work well in places where we have few conflicts with driveways. I first saw the Mixing Zone during a visit back in November 2010 and it seemed to work exceptionally well and I felt extremely comfortable when cycling in the cycletrack. It also eliminates the need for a specific phase for people on bikes, so you end up with a traffic engineering win-win.