To get there, I hopped the Yellow Line into downtown Portland, got off, and rode over the Tillkum Crossing Bridge, the newest of Portland's bridges (completed 2015), and the first bridge in the USA designed to be used exclusively for public transit, bicyclists and pedestrians.
A huge mountain of clouds grabbed everyone's attention and lots of folks stopped to gaze in wonder.
Because the entrances to either end of the bridge involve multi-modal transportation -- including lanes for private cars, which cannot go on the bridge but are diverted elsewhere -- people need to be especially careful and obey ALL signs and crossing signals. Definitely stow the iPad and ear buds while riding through this area, since MAX [light rail] and the Portland Streetcar are both pretty damned quiet and you will never hear them coming if your ears are clogged.
contact the folks at PBOT with comments, questions and concerns about the infrastructure in place here (and elsewhere in the city). Though Tillikum Crossing was completed in September 2015 and is rapidly becoming a popular crossing for walkers and bikers, I suspect more refinements are in the works, so stay tuned.