Second Boston question

A look at the subway map shows a new line: the Grey line. We will need it
to get to the convention center at the World Trade Center stop on Summer St.
I'm a bit confused by the line. The MBTA web site seems to indicate that
it's really a specialized bus that runs along a dedicated roadway with
subway like stations. It's been a while since I've been to Boston and it
was not there at the time.

The web site also seems to show that the line is in two segments, not yet
connected. Each segment connects with either the red, orange or green line.
Coming in from Cambridge on the Green Line (if we do it that way) there
appears to be no direct link to the World Trade Center bound grey line
segment. It looks like you first have to go over to the Red line and go a
couple of stops.

Anyone with experience about the Grey Line? Is the route in from Lechmere
Station on the Green Line to the World Trade Center bound Grey Line a
problem? How long should the trip take?

Any advice is appreciated.

Oh...and I still have not received advice about the neighborhood by
Monsignor O'Brien Hwy in Cambridge. Is the area safely walked, especially
in the evening?

Thanks.

--
Bill in Schenectady

....
the Grey line.

Silver Line?

Yes, I guess it's the Silver Line. Went to the MBTA web site and it
looked grey to me!