This was an Obama stimulous project. It was to save 10 - 15 minutes on the SEA/PDX route
So $181M / 15 minutes means this project cost $12.1M per minute saved.
Seems like a good investment of the tax payer's money to me.
There were several reasons for the new 14 mile route.
The old route ran on a BNSF freight track. Freight has priority over passenger. The old route ran between the Nisqually Reach (a body of water) and a series of cliffs. For several years rocks falling on rails was a constant maintenance problem on that stretch of track. The new route was built on an abandoned section of BNSF right-of-way. Along the new section of track, no freight traffic to wait for, no boulders on the tracks and a savings of 10-15 minutes of run time.