Jori Adkins, Jim Merritt, and Apex Engineering have done some great professional work creating a 'post and beam' alternative to the ill-conceived Sounder 'berm' crossing of the Dome District in Tacoma and put it up on a website.
This stands in sharp contrast to the City's current position, as I hear it, that you can't use the area under the Post and Beam for anything. In addition the Sound Transit plan violates the City of Tacoma's Comprehensive Plan on both initial trail planning and the new but promising 'habitat corridor' designation which is designed to work well in denser areas.
Sound Transit does have a plan for a pedestrian connection - at 'A' Street, but this is basically a connection to nowhere, unless there is a major redesign of I-5 in this area.
Berms have construction problems as well - greater utility relocation is a very common place for costs to escalate and building close to the berm has issues with that structures 'load' profile.
Perhaps the biggest problem with the Sound Transit design is aesthetics - they are taking a rural rail design and plopping it down through the 2nd largest urban center in Western Washington. Imagine, if you will, a 20-40 foot high 'mountain' of dirt running down the middle of the street by your office - with a trash collecting fence.
The arrogance of Sound Transit in responding to this professionally prepared alternative isn't too pretty either. Not to mention also fiscally irresponsible.