If I remember the story ...

ODOT wanted to substantially upgrade the highway, but knew it was going to be a big project with geological challenges due to 100 inches of rain annually, steep hillsides and layers of the infamous blue goo clay of the coast range. A typical contract would have the government agency or consultant designing it, and then putting the contract out for bid. Many contractors will bid a project like this at break even or possibly a small loss, with the full expectation that they will make a profit on the inevitable change orders.

In this case, ODOT tried a design-build contract where a single primary contractor is responsible for both the design and construction of the project with the only specifics being the required final result, some restrictions and a completion date. This is not that unusual, because it allows the contractor to make the required changes as construction progresses. In many cases, construction begins before the entire project is fully designed which also expedites construction.

When the contract was awarded, I recall it being protested by at least one losing bidder - not that unusual in government contracts. One of the concerns was the scoring system ODOT used to determine a bidder's qualifications, and Granite's geological expertise was in question.

By the looks of it, Granite designed an everyday highway figuring they could just build bridges and move a gazillion cubic yards of rock and dirt without showing the proper respect for the rain and blue goo. The coast range has very unstable ground that can start moving whenever it wants. Best bet is to tread lightly and realize you will have constant landslides, hopefully small enough to compensate.

The alternate fill and culvert plan will probably require constant maintenance and rebuilding every few years as the ground continues to shift.

I did find an older article: Older US 20 article LINK

Notice some key components:
* Upgrade to allow 53 foot trailers on semis.
* Probably had bike lanes, increasing bridge and highway width. The bike lobby is HUGE here in Oregon, especially on the west side.
* The project must have required moving the railroad as a new bridge for them is mentioned.

I don't recall the financial arrangements for this. I think it was cost plus with a limit.