It seems to me like the simplest solution would be to run all light rail through the existing transit tunnel. I know it would be a lot of traffic but they've said they can upgrade the signalling system to help.
Seattle's light rail expansion is complex. Misunderstanding it is allowing politicians to hang vanity projects on the plans that wreck connections and boost delays. Let's debunk.
This article gives more information on this idea https://www.theurbanist.org/2023/02/07/build-ballard-link-fa...