Once you factor in the best fit route, including through both major cities, seismic and land surveys, figuring out and plotting of new bridges, figuring out who owns what and how to best double existing track with a new high speed track, getting land for a new yard.
I can see planning hitting that much, yeah.
Hell, if we're using the Amtrack stations it has to tunnel under modern Seattle, as well as figure out how its getting through to downtown Vancouver across at least one river crossing in a busy and populated area.
Also, consider how much the conservatives under Christy Clark spent to get the evergreen line built and the pre-build surveys cost well above the 10 million dollar range and were completely wrong and lead to massive cost overruns. Edit: The underground area in question was roughly 6 blocks long.