I wonder if there is any feasible and affordable engineering solution to build a new restaurant and ample parking somewhere on that island?
It took a lot of design and engineering just to fit the 2nd tunnel on the island. If they tried to refit the restaurant on there it'll probably be the world's most costly restaurant design!!
I agree. Initially they were going to expand both islands to accommodate the about 250 foot spacing between the two bridges. That would be needed for the immersed tube construction method which would require that much separation in order to dredge the trench for the new tube without impacting the existing tube.
By using the shield-bored tunnel method (first time in the H.R. area) they can get much closer to the existing tube and thereby place its portals on the existing islands. Plus save about $200 million.
Building those 4 islands on what is essentially open sea was considered one of the most remarkable portions of the project, also very expensive. The same challenges would occur on expanding an island, massive amounts of suitable soil fill material needs to be obtained from somewhere, barged out there, and then placed layer by layer and properly compacted, and massive amounts of armor stone needs to be barged out there and placed around the island.
They must have built the islands very well, as I have never heard of them being damaged in any storm, other than perhaps some cosmetic damage, and they have been there for 53 years.