Diagramming station depths

Sound transit has a blog post up that pairs well with our recent discussions of transfers and deep stations:

As people have begun to study the recently published Draft Environmental Impact Statement (DEIS), some have wondered about the depths of the stations and what the rider experience would be like to access the platforms and transfer between lines.

There are several factors in the Downtown segment that influence the depths of the tunnel stations.

In addition to physical considerations like existing terrain, soil properties, and existing underground infrastructure or building foundations, geometric design constraints imposed by the depths of adjacent stations also may determine how deep underground a station must be built.

Click through for a visual comparison of the station depths. You can see that a shallow" station on 4th in the CD would be deeper than Capitol Hill, for example. Or that a deep station in the CID would require an even deeper Midtown one.

Regarding Midtown, one interesting idea that's stuck with me is, given the steepness of the hill, a street-level entrance on 2nd & Madison, with a long pedestrian tunnel, could connect directly to a 5th & Madison station that would otherwise be only accessible by elevator.