Just a cool video on tunnel clearance enlarging that I ran across in some research on the NS Heartland Corridor project…thought I’d share.
Pretty cool.
I wonder why they did not lower the floor instead?
Because then they wouldn’t have had the chance to use that cool rock grinder thingie!
That is a very cool vid! BTW, they are using different methods to improve clearances in the various tunnels along the corridor, depending on how the particular tunnel is constructed. I had a PDF with about 20 pages of info per tunnel, but can’t find where I saved it. Here is another PDF I found…
http://www.ctb.virginia.gov/resources/Agenda_Item6_Heartland_CTB_Update_Dec2006_short.pdf
…that shows on page 14 all of the deifferent methods being used. Jamie
Very interesting - and informative. Thank you.
This sort of operation would be a cool choice for ‘window in the fascia’ modeling - a second dummy bore parallel to an existing single track tunnel on the layout.
As for why it’s easier to raise the roof than to lower the floor, there are foundations under the sidewalls that wouldn’t take kindly to losing their lateral support. Also, the track level and alignment isn’t impacted by roof raising - possibly a critical factor if curves are tight and grades are close to or at the ruling grade.
Chuck (modeling Central Japan in September, 1964 - with a planned TBM in a fascia window)
One reason they may not lower the tunnel floor is that most of these tunnels are in constant use. They can take it out of service for a few hours at off peak times do some work, clean up and put it back in service. If they lowered the floor that would require removing the track, major excavation and replacing the track with tunnel being out of service for an extended time. This is assuming there are no other structural issues.
I suspect there are also drainage issues with tunnels, so that lowering the floor might not be the best thing to encourage drainage. I remember hearing one time that drainage and freezing of water within tunnels are two of the reasons why tunnels are such a PIA to railroads. On this Heartland initiative, they’re actually daylighting one tunnel, I think railroads would in an ideal world daylight every tunnel they can.
Great slide show on the NS Heartland Corridor, thanks. These “corridors of the future” both NS and CSX have initiatives under way on the East Coast - I think they’re another competitive indication of why the coming years may be the new golden age of railroading, as opposed to the trucking age of the last 40-50 years.
If you have ever driven down I-81 in the Shenandoah Valley, you’ll know why we wish like heck that they get some of those trucks off the road. It’s non-stop truck congestion. Hoping they proceed with the I-81 rail initiative too.
the machine doing the cutting is called a road header… it is used in mining to cut thru rock in the coal industry ( yes i am a miner ) they are usually used for forming the tunnels into the coal seam or to cut thru faults or dykes
the method of cutting is all due to GRAVITY the tunnel has stresses imposed upon it from all sides if you remove the floor you must remove the track cut the floor and re concrete then relay the floor this will result in a 3 foot step… NOT POSSIBLE to run trains … it is far easier to support the walls ( ribs ) with bolts then excavate the roof to the profile then bolt the roof this will result in a step in the roof … however this will not stop the trains as opposed to the floor method
in the video you will note that one of the workers has a long metal rod in his hand … it looks to be approx 10 foot long this will be one of the bolts inserted into a drilled hole and chemical used to anchor the bolt then the bolt is tensioned… of note is the length of the bolt in stable strate no bolt is reqd in unstable ( faulted ) ground longer bolts are reqd… the mine i was working at last week was using upto 11m long fully grouted bolts that can hold 55 tons