Stel -- that is an intriguing combination of companies and their expertise
Your speculation might be in order -- However, my guess is that if its a tunnel it will be for something akin to the plaza next to Memorial Hall in Harvard Sq. with Cambridge Street running below
I found a draft of the Harvard Allston IMP from last decade. It shows the proposed route of a transit tunnel:
> running along the west side of the stadium,
> angling SE between the stadium and the outdoor track,
> crossing N. Harvard St.,
> continuing SE through the east portion of the original Charlesview (very close to New England Book Depository (red brick building just to east of the original Charlesview that was supposed to be demolished, but perhaps not now)),
> crossing Western Ave between the old WGBH south building and the east section of the science complex,
> crossing Rotterdam St.,
> continuing SSE to the east of the residences on Windom St.
> crossing Cambridge St., where the map ends.
On the other side of the Charles, I believe most of the tunnel already exists; it ends at Mt. Auburn and Elliott.
Google maps is quite current for this area; it shows the old Charlesview completely gone, and Continuum built out structurally. Klarman looks to be going in the parking lot east of Spangler. Burden is the irregularly shaped building to the NE of Spangler. The map shows the very large area of strange pipes and vents south of Western Ave and east of Rotterdam that Beeline has photographed. Almost certainly, this is ongoing remediation of subsurface environmental contamination.
