🚀 go-pugleaf

>Does anyone know why, at Harvard Square, Outbound is up and Inbound is
>down, but at Porter Square, Outbound is down and Inbound is up?

Clearances, apparently.  The turn at Harvard is too tight to allow parallel
tracks and platforms.  (The two levels there date from before the extension,
by the way.)  The width of the tunnel up to Porter was also constrained by
the need to do all of the work under Mass Ave with the absolute minimum of
digging under existing buildings.

The Porter station is so deep partly because Porter Square is on a slight
hill and also because it has to go far enough under the commuter tracks to
allow supports for the trains on those tracks.  (Regular trains, particularly
freights, are much heavier than rapid transit.)

By the way, on many buildings along the route of the T extension, you will
see attractive circular tiles firmly affixed to the walls near the doors.
The T did this so that in case any of the buildings started to settle, the
tiles would crack an as soon as the walls or door frames started to warp
before there was serious structural damage so they'd have time to do
something about it.
-- 
John R. Levine, IECC, POB 349, Cambridge MA 02238, +1 617 492 3869
johnl@iecc.cambridge.ma.us, {ima|spdcc|world}!iecc!johnl
Re-elect Vice President Potatoe-Head !