Construction Techniques

What is an easier way of tunneling x number of feet (like 1,000 feet):

Cut-and-Cover

OR

Drill-and-blast?

either way it will take 10-15 years to complete

Cut and cover is an inherently easier way to construct tunnels, you just dig a big hole, lay tracks, and put a road on top. Drilling and blasting is not only more expensive, but it also takes longer.

However in today's NIMBYistic world, large-scale cut and cover projects are not always well-recorded by the local population, so more likely than not they will choose tunnelling.

Sometimes they have no choice, like ESA.

lirr42 wrote:ometimes they have no choice, like ESA.

Is this because the 63rd street tunnels were so deep anyway?

When Amtrak extends the current "tunnel box" from 11th avenue west to 12th avenue, is it more likely to see cut-and cover construction or drill and blast?

Thomas wrote:When Amtrak extends the current "tunnel box" from 11th avenue west to 12th avenue, is it more likely to see cut-and cover construction or drill and blast?

This is the LIRR forum...

Were any of the LIRR Tunnels to Grand Central Terminal constructed using drill-and-blast?

No.

http://www.youtube.com/watch?v=ms0nDGDrNc8

Cut-and-cover is only cheaper than bored or mined tunnels when you don't have to move too much out of the way. Since Park Avenue, Metro-North, and a slew of historic buildings are not moving, rock TBM's made the most sense. Similarly in Queens, Sunnyside Yard and Harold Interlocking are hard enough to move stuff for the approaches, so again bored tunnels. In the former Yard A, nothing in the way, so a big open cut that also allowed for the TBM launching and support. It is being filled in with structure now.

jlr3266 wrote:Cut-and-cover is only cheaper than bored or mined tunnels when you don't have to move too much out of the way. Since Park Avenue, Metro-North, and a slew of historic buildings are not moving, rock TBM's made the most sense. Similarly in Queens, Sunnyside Yard and Harold Interlocking are hard enough to move stuff for the approaches, so again bored tunnels. In the former Yard A, nothing in the way, so a big open cut that also allowed for the TBM launching and support. It is being filled in with structure now.

1. I was under the impression that the tunneling segments just north of Grand Central Terminal were created from drill-and-blast?

2. What is the typical maximum depth for a cut-and-cover tunnel?

One or two track levels below all the water/utility lines.

How deep are the water/utility lines?

How deep are the water/utility lines?

All underground utility,water and sewer lines are as deep as required by city codes,ranging from 5 ft till 15 ft as needed.

Backshophoss wrote:ll underground utility,water and sewer lines are as deep as required by city codes,ranging from 5 ft till 15 ft as needed.

Under street level or buildings' basements?