The Knik Arm bridge has been a subject of concern for over 40 years. With the money the state has spent on "studies," the proposal by Dames & Moore (engineering firm here at the time), I'll bet their "causeway" could have been built and paid for.
They first proposed a bridge or tunnel across the narrowest point but concluded that the widest point would be less expensive because the water flow would be the slowest. The rocks could be hauled from Chugiak area by rail and dumped without a long truck haul.
I'm sure a little research could resurrect their plan, and it deserves to be considered.
— Vera Crews
Anchorage