Quote:
Originally Posted by hat
I'm really hoping the city will consider something like this. |
Keep in mind if you are tunneling under existing buildings you have to consider the foundation depth and settlement implications. That route would push the stations very deep. For example it would run right under the Fox Tower which the bottom of the parking garage is 65' below grade. Then you have to go down even further for foundations and/or piles and whatever additional depth to mitigate any foundation settlement concerns. Unfortunately, PDX doesn't have bedrock near the surface like some other places (NYC) that makes tunneling beneath structures much more practical.
That would put any stations very deep and likely only accessible by elevators. Ideally they'd align the route beneath roads where possible and keep any corners below buildings with limited foundation depth to keep the stations closer to the surface so that they could also be served by escalators.
Also, any tunneling under private property presumably would need an easement (i.e. $$$) as well as potentially limit future development options for underground work and/or make future building over any subway more complex and expensive.
The SW extension really should be going under OHSU and then could continue under the park blocks through PSU. I think the chosen alignment is so short sighted at best.