Anyone know what new tunnel technology they're talking about here?

[Ed Kapuscinski]

Recent advances in engineering now make it possible to increase the tunnel's clearances with much of the construction underground and for much less money, Renjel said.

http://www.baltimoresun.com/news/maryland/baltimore-city/bs-md-ci-double-stack-plan-20160414-story.html

Has there been some fresh new tunnel enlargement technology developed?

[Catt]

If they are going to be underground for most it I would think the plan is to dig out the floor of the tunnel and lower the rails to get the clearance needed.Not the first time the technique has been used,but maybe the first time on the east coast.

[Hamaker]

I'm not sure if this is what they are talking about, but I always thought they raised the 'ceiling' of a tunnel.  Found out they drop the level of the track to gain the additional needed clearance.

[Hamaker]

Opps !  Catt beat me to it !

[C855B]

I have to wonder if they're talking about a variation on the tunnel boring machine, a/k/a "mole", being used for the Seattle tunnel project. This is a "recent... engineering" project in the news. It would make sense in the Baltimore case. While the mole has been fraught with issues and I believe the whole project is months behind due to machine failures, the concept on a smaller scale dealing with an existing bore would make a lot of sense.

Speaking out of my @$$, of course, just putting a possible two and two together. :shoulder-shrug:

[Ed Kapuscinski]

I mean, that's what I would've assumed too, but remember, this is a tunnel through the middle of downtown Baltimore, so it's not a situation where they can really just chew through rock or dirt. I think there are tons of utilities, etc... that made the initial approach of a few years ago (the one that would cost in the billions) so difficult.

[John]

It's easy .. just put a cross over in between the main and the light rail line right at Ravens stadium .. and run north bound freights up howard street in between the street cars, and the southbound thru the tunnel 

[Ed Kapuscinski]

I'm into it.

[learmoia]

If they are going to be underground for most it I would think the plan is to dig out the floor of the tunnel and lower the rails to get the clearance needed.Not the first time the technique has been used,but maybe the first time on the east coast.