Options for the Bethesda Tunnel

CCCT has a pretty complete rundown of the various options for the CCT through Bethesda if the Purple Line is built.

There's the sidewalk/surface route, which might be coupled or not. The sidewalk doesn't immediately help cyclists, but it does preserve the trail tunnel as a placeholder.

MTA has determined that it is feasible to have a sidewalk alongside the Purple Line in the tunnel. MTA presented drawings showing the planned sidewalk at the December 18, 2012 Bethesda neighborhood focus group meeting, now available on their Purple Line websitewww.purplelinemd.org.

The surface route would probably be a cycletrack.

The design of the CCT surface route is ongoing, but will likely include a full width cycletrack along the north side of Bethesda Avenue..., a redesigned intersection and crosswalk at Wisconsin Avenue with traffic signal changes to give better protection from motor vehicle traffic turning across the crosswalk, a cycletrack or shared-use trail along Willow Street, and an off-road shared-use trail through Elm Street Park. The goal is to have this in place before the CCT tunnel route is closed.

And then there is a new proposal for a different tunnel beneath a rebuilt Apex Building

The idea is to rezone the Apex Building to permit a much taller building at that location, raze the existing Apex Building, build the Purple Line Station and Trail without the cost and risk of doing so under the existing building, then build a taller building over the station and trail in place of the old building.

But it would not follow the current route and not go below the Air Rights Building.

A new tunnel alignment that is not under the Air Rights Building would be needed to take full advantage of razing the Apex building. There is one such alignment that might be possible for a trail-only tunnel that is under consideration at M-NCPPC

A new tunnel for the CCT could be built south of the existing tunnel, from the west side of Elm Street Park to under the (rebuilt) Apex Building, by going under Elm Street for one block and under Wisconsin Avenue. This alignment would avoid foundation structures of the Air Rights Building and could allow cut-and-cover tunnel construction. The Purple Line would be in the old Air-Rights tunnel as planned now. The cost of this new, separate CCT tunnel could be more than offset by the reduction in construction costs of the Purple Line and CCT overall if the Apex Building is torn down.

CCCT is not 100% sold on this yet - until they know what the tunnel would look like. And they seem to be worried about how taller buildings might change the area

The owner of the Apex Building would need permission for a very significant increase in building height to be motivated to tear down the existing building and rebuild. The owners of the other buildings on this block might also receive permission to build to a higher density, since the proposed Master Plan Ammendment is likely to consider other properties on the block. Buildings on both the north and south side of the Woodmont Plaza could become even taller than now planned.

Comments

[SJE]

I propose Parson's Brinckerhoff to design the new station and Foulger Pratt to build it, with oversight by MoCo. That way we can be sure of quality, on time and on budget.

[Crickey7]

I confess to being a little concerned about the Purple Line going into that tunnel given the support columns that are currently there. I have a strong suspicion that we will discover that significantly more support is needed for the building overhead, with commensurate cost increases.