There are calls for Seattle Department of Transportation (SDOT) to hire also an engineering firm with Immersed Tube Tunnel (ITT) expertise next to HNTB hired by SDOT to asses the West Seattle Bridge replacement options, be it a bridge or an ITT.

In an Op-Ed published in Westside Seattle, Bob Ortblad, a local citizen an an retired civil engineer championing the ITT option, writes that current consultancy firm HNTB are basically bridge builders and their inclination will naturally be building another bridge. For a level play, SDOT should also hire another engineering firm equally qualified in immersed tibe tunnels he says.

Ortblad, a keen prometer of the tunnel option goes on saying that "an ITT is a much better option because it can be constructed in half the time, at half the cost of a bridge, accommodate light-rail, and be much safer in an earthquake.  An ITT can also restore a bit of scenery and tranquility to the Duwamish River."

https://www.westsideseattle.com/robinson-papers/2020/09/08/op-ed-west-seattle-cable-stayed-bridge-vs-immersed-tube-tunnel