At one point does a long underpass become a tunnel?

[Pete from Boston]

what about Klyde Warren Park in Dallas? right on the edge of tunneldom or just a long cut and cover?

Well it's definitely a cut-and-cover; the question is essentially whether cut-and-cover structures in general are a type of tunnel. However, I'm inclined toward "tunnel" on this one, because of what some others have said above: the use of the space above the road isn't related to the road. If they brought a bunch of dirt and built a mountain where that park is, you'd have no problem calling this a tunnel, though it would be the same structure.

I don't think there's much debate that there are cut-and-cover tunnels.  There are miles and miles of subway tunnels in places like New York and Boston that are cut-and-cover, and nobody questions whether these are true tunnels.  The definition of "tunnel" has to do with shape and function, not construction technique.

[empirestate]

what about Klyde Warren Park in Dallas? right on the edge of tunneldom or just a long cut and cover?

Well it's definitely a cut-and-cover; the question is essentially whether cut-and-cover structures in general are a type of tunnel. However, I'm inclined toward "tunnel" on this one, because of what some others have said above: the use of the space above the road isn't related to the road. If they brought a bunch of dirt and built a mountain where that park is, you'd have no problem calling this a tunnel, though it would be the same structure.

I don't think there's much debate that there are cut-and-cover tunnels.

I don't think so either. I think the distinction would be not whether all cut-and-cover structures are not tunnels (we agree that's false), but rather whether all cut-and-cover structures are tunnels?

Of course, it seems you would make the same distinction, so maybe the question isn't that after all. To me, it still all comes back to "through"-ness.

[hubcity]

I always assumed those apartments are some sort of public housing.

They were quasi-public (middle-income residents were the target audience) under a subsidized mortgage plan. They're now straight-out rentals, with about 15% of them as Section 8 (low income) housing.

Their addresses are: 260 Audubon Avenue, 1370 St. Nicholas Avenue, 1365 St. Nicholas Avenue and 111 Wadsworth Avenue.

Info could have changed - it comes from a 2004 NY Times piece, here: http://www.nytimes.com/2004/06/18/nyregion/life-on-the-road-learning-to-sleep-as-trucks-roar-through-basement.html?pagewanted=all

[Bruce]

Would any of you guys consider a capped lid (with a park or buildings on top of it) a tunnel? I don't really have a preference, but at some point (e.g. the I-90 Lid on Mercer Island, WA) it's long enough to really be a tunnel.

[mrsman]

Would any of you guys consider a capped lid (with a park or buildings on top of it) a tunnel? I don't really have a preference, but at some point (e.g. the I-90 Lid on Mercer Island, WA) it's long enough to really be a tunnel.

IMO, history would play a big factor over whether something is a tunnel or an underpass. 

1) If they simply put land ontop of an existing open-cut freeway (ex. I-10 near Downtown Phoenix) then it is an underpass, regardless of length - even if it feels like a tunnel.  Similarly, constructing an airport runway strip over the highway alignment is not a tunnel either. 

2) If the freeway went under existing terrain, then it is a tunnel.  Ex. the Squirrel Hill tunnel in Pittsburgh. 

[jeffandnicole]

Would any of you guys consider a capped lid (with a park or buildings on top of it) a tunnel?

Generally, they are known as cut-and-cover tunnels, so yes.

In my opinion, if they have to build fans into the tunnel for air movement, then it's a tunnel, no matter what is above it.

[vtk]

Would any of you guys consider a capped lid (with a park or buildings on top of it) a tunnel? I don't really have a preference, but at some point (e.g. the I-90 Lid on Mercer Island, WA) it's long enough to really be a tunnel.

IMO, history would play a big factor over whether something is a tunnel or an underpass. 

1) If they simply put land ontop of an existing open-cut freeway (ex. I-10 near Downtown Phoenix) then it is an underpass, regardless of length - even if it feels like a tunnel.  Similarly, constructing an airport runway strip over the highway alignment is not a tunnel either. 

2) If the freeway went under existing terrain, then it is a tunnel.  Ex. the Squirrel Hill tunnel in Pittsburgh.

I like this test. But what if a trench is dug for a highway, and then decades later, a cap is constructed with a park on top which approximately restores the original terrain?

[empirestate]

IMO, history would play a big factor over whether something is a tunnel or an underpass. 

1) If they simply put land ontop of an existing open-cut freeway (ex. I-10 near Downtown Phoenix) then it is an underpass, regardless of length - even if it feels like a tunnel.  Similarly, constructing an airport runway strip over the highway alignment is not a tunnel either. 

2) If the freeway went under existing terrain, then it is a tunnel.  Ex. the Squirrel Hill tunnel in Pittsburgh.

I think that's a fair assessment. But how much of that is history and how much is simply construction method? In other words, if the Squirrel Hill Tunnel were cut-and-cover, would it still be a tunnel? What if the road was bored under the airport runway after it was built?

Looking at it another way, would that mean the rail yard under Grand Central is not a tunnel, because it existed in an open-air state before streets and buildings were built above it?


iPhone

[Pete from Boston]

Would any of you guys consider a capped lid (with a park or buildings on top of it) a tunnel? I don't really have a preference, but at some point (e.g. the I-90 Lid on Mercer Island, WA) it's long enough to really be a tunnel.

IMO, history would play a big factor over whether something is a tunnel or an underpass. 

1) If they simply put land ontop of an existing open-cut freeway (ex. I-10 near Downtown Phoenix) then it is an underpass, regardless of length - even if it feels like a tunnel.  Similarly, constructing an airport runway strip over the highway alignment is not a tunnel either. 

2) If the freeway went under existing terrain, then it is a tunnel.  Ex. the Squirrel Hill tunnel in Pittsburgh.

Clearly not a definition embraced here:


Pru Tunnel:
https://en.wikipedia.org/wiki/Prudential_Tunnel
.6 mile, trench covered with buildings

Dewey Square Tunnel (now subsumed by the Tip O'Neill Tunnel):
https://en.wikipedia.org/wiki/Dewey_Square_Tunnel
.45 mile, trench covered with surface road

Both fit in your category #1.