Years ago, I was associated with a project that would have built a rail system from downtown Seattle to its eastern suburbs across Lake Washington as well as north/south routes. Voters in the suburbs supported the idea; downtowners rejected. It never got built.
The result: One of the most congested north/south freeways in the US and the construction of two more bridges across the Lake.
I think we should choke this one down in view of Honolulu's prospective future. I wager that if it is built future decades will see it extended with enthusiasm.