From a quick look at sat images it doesn't seem like it should be difficult to build a normal segregated bicycle path that can safely support 18+ mph speeds. Dutch, Swedes, Danes, Fins, and many others can do it, are Seattle traffic engineers that much less competent?
The parking lots would be safer for all users if they are one-way angled back-in. This will also buy several feet of ROW for a wider bicycle path.
The bicycle path should have the same ROW as adjacent motor traffic lanes. Where the path crosses drives, parking lot entrances, or minor roads the motor vehicles should have sharks teeth to indicate that the bicycle path has ROW. The path should also be consistent material, color, and grade with crossings rising or lowering to meet the path which also helps insure that drivers are aware of it and provide appropriate ROW.
How wide are the vehicle lanes? Can they be narrowed to buy more path width?
Last edited by CrankyOne; 05-27-14 at 04:15 PM.