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Ulrich
| Why two separate bores? Posted by Ulrich on Monday, May 18, 2009 4:04 PM http://www.carrtracks.com/tnl5343.htm Why two bores? Why not one tunnel with two tracks?
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henry6
| Posted by henry6 on Monday, May 18, 2009 4:10 PM Our DRGW addicts probably have the best...and correct...explanation. My guess would be grades inside the tunnels are different depending on prevailing direction of loads and/or grades leading into the tunnels on the opposite end are at different levels. At least those are the usual reasons RIDEWITHMEHENRY is the name for our almost monthly day of riding trains and transit in either the NYCity or Philadelphia areas including all commuter lines, Amtrak, subways, light rail and trolleys, bus and ferries when warranted. No fees, just let us know you want to join the ride and pay your fares. Ask to be on our email list or find us on FB as RIDEWITHMEHENRY (all caps) to get descriptions of each outing.
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john_edwards
| Posted by john_edwards on Monday, May 18, 2009 4:13 PM I'm going to guess that one tunnel was there and they needed two (tracks), so rather than shut one tunnel down for expansion they just drilled another. John
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BaltACD
| Posted by BaltACD on Monday, May 18, 2009 4:43 PM Not a DRGW addict. My best guess would be that one bore was done with 'Git-R-Done' haste in the initial construction of the line as a single track route. When traffic density and construction monies became necessary and available, a second tunnel was bored. By boring a second tunnel traffic could still be maintained on the original tunnel during construction of the second tunnel. Keeping the line open and hauling traffic is the name of the railroading game. To have enlarged the original bore to double track standards would have cause the original bore to have been shut down for at least signifigant portions of time to allow the construction crews to do their jobs. Much simpler and probably more economical to just bore a entirely new tunnel. Never too old to have a happy childhood!
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corwinda
| Posted by corwinda on Monday, May 18, 2009 5:14 PM It's also a lot easier to keep the roof up for a single track tunnel than one twice as wide.
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Monday, May 18, 2009 5:32 PM A little searching for "Kyune" & "tunnels"& "D&RG" yielded results that indicate that the 2nd tunnel was probably drilled/ completed in 1913; the 1st one as part of the line's original construction in the 1880's (or so). A review of a detailed history of that line (which I haven't done yet) will probably indicate that the 1st tunnel was simply was "developmental" = to get the railroad built; the 2nd tunnel was for additional capacity, just as the other posts above indicate. And unless the rock conditions are very favorable, a single-track tube or boreis preferable for structural reasons - they are more nearly circular than a double-track bore which would be elliptical, with itsleast-strong dimension in the horizontal plane, where the overburden load of the mountain above has its greatest effect. Pretty much every situation I've seen with 2 tunnels above water, they were drilled at different times.There are a fair number of underwater tunnels that were done at the same time, though - the PRR's under the Hudson (North) River about 100 years ago, and the English Channel Tunnel about 20 years ago are just 2 examples of those. There may be some exceptions over in Europe or Japan, but even if so, drilling 2 at once isonly a recent practice. As a practical matter, the best tool to drill a tunnel is another tunnel, with a railroad in it - even or esp. with a narrow-gauge industrial railroad. Even initial tunnel contractors will often drill a pilot tunel, either as part of the main bore or parallel to it, to accomplish that first. Then it's a whole lot easier for removal of excavated/ waste rock and carrying in of the installation materials, plus equipment moving and supply, etc. Unless there's some drastic time constraint to get 2 bores in service ASAP or an easy alternate routeto the other side - both rareto non-existant conditions for most mainline U.S. railroad tunnels - that's why tunnels are drilled 1 at a time. - Paul North. "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Railway Man
| Posted by Railway Man on Monday, May 18, 2009 5:36 PM
Because it is cheaper, faster, better in almost all cases. Double-track tunnels are uncommon in North American railway practice because there are very few double-track railways built new in North America -- almost all American railways were built as single track and later double-tracked. Double-tracking an existing single-track tunnel is anywhere from 100 times more expensive than building a second single-track tunnel because of the construction staging problem: How do you keep trains running through the tunnel while you enlarge it? Even without the staging problem, the cost of a double-track tunnel can be much greater than two single-track tunnels because the roof support problems are much larger in incompetent ground. Examples of double-track tunnels in North America are almost entirely on new alignments built to replace an existing double-track or single-track alignment, where the construction staging problem went away because there weren't any trains. The classic examples are the Magnolia Cut-Off on the B&O and the Bayshore Cut-Off on the SP; there's also a lone double-track tunnel on Donner Pass dating to the Harriman improvements of post-1900. But for every one of those, there are dozens of paired single-track tunnels, e.g., Donner Pass; UP Weber and Echo Canyons; D&RGW Soldier Summit (example shown in this photo); UP Blue Mountains. On Soldier Summit there are three paired tunnels -- the two in the Price River Canyon are Nolan and Kyune (the pair shown), and the Thistle Tunnels. The original line was narrow-gauge laid 1881-1883. It went around these canyon ribs that Nolan and Kyune tunneled through. The line was standard-gauged single-track in 1890 at which time the first Nolan and Kyune Tunnels were drilled because the narrow-gauge curves were too tight and the embankments were too wash-out prone. The second track was built in 1913-1914 at which time the pairs were built. Thistle Tunnel, which dates to 1983, has exactly the same rationale. The first bore bypassed the Thistle Slide; the second bore was constructed after the first was placed in service. It would have been feasible to build a single double-track bore at Thistle but the time delay to get it built compared to a single-track tunnel -- and getting a shut-down railroad back in service -- was economically inferior. RWM
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Deggesty
| Posted by Deggesty on Monday, May 18, 2009 7:20 PM
Another example is N&W's new line through Elkhorn Mountain, which was constructed in the 1950's. This line reduced the grade considerably, and made it possible for the N&W to retire its electric locomotives. I doubt that any of you non-N&W employees will have the opportunity, but I advise against passing an eastbound coal train enginein the tunnel, especially if you also are eastbound: the noise is more than deafening. Johnny Johnny
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Railway Man
| Posted by Railway Man on Monday, May 18, 2009 7:32 PM
Excepting the very long tunnels such as Moffat, most American railway tunnels in the 1860-1930 era were driven full-face without the pilot bore or pilot heading unless they were in extremely heavy ground. In poor ground sometimes the tunnel was driven with an upper face (the arch) advancing about 5-10 feet ahead of the bench (the straight part) because there was so much overbreak that this made it easier to crib the timber sets between the arch and the back before breaking out the tunnel to full face. As an aside, most North American railway tunnels are essentially 100% self-supporting except within a few feet of the portals where there is heavily weathered rock. The rock forms a natural arch. Even siltstones and claystones so soft I can snap inch-thick pieces with the fingers of one hand, will often self-support for awhile, sometimes even a few decades, if you don't mind a slow dribble of rubble falling off every now and then. Tunnel lining, where it is used, is in almost all cases serving solely to support only the superficial rock. It keeps pieces of rock from gradually spalling off and falling onto the track as it weathers; that is, the lining is not supporting the mountain (except right at the portals, and then only a few feet worth). The same thing can be accomplished with rock bolts and shotcrete. With timber or steel sets, the idea is to keep the superficial rock snug up so that little cracks don't slowly become big cracks and slabs of rock let go. The idea behind rock bolts is to tie the last few feet worth of rock into the mass. With both methods, the idea is to prevent the tunnel from gradually enlarging itself and put loose rock onto the track, where it might derail a train. Oxygen exposure and moisture are enemies of competent rock; by encasing the whole thing in shotcrete the weathering action is slowed down a great deal. RWM
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corwinda
| Posted by corwinda on Monday, May 18, 2009 9:19 PM Modern tunelling methods (tunnel boring machines like was used for the Thistle tunnels) increase the economic/technical advantages of two single tunnels over one double track tunnel. With a TBM; one double track tunnel approximates 4 times the material removed of one single track tunnel. And then you would have to almost half fill the tunnel with something - probably ballast - to get the track to the widest level of the bore.
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jclass
| Posted by jclass on Monday, May 18, 2009 9:50 PM The Hoosac Tunnel was built by the State of Mass. in the 1880's. Later sold to the Fitchburg (B&M). It was and isa single bore with one track the first five or six years, and a second then added.The tunnelwas laterelectrified. Electrics would pull the steam enginesplustrains through the tunnel. My grandfather nearly died while riding a passenger trainthrough the tunnel. The porter had neglected to close a passenger car window; smoke filled the car. I don't recall ever seeing an article in Trains orelsewhere going into detail about this electrification. The catenary remained in place well into the forties.
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dldance
| Posted by dldance on Monday, May 18, 2009 9:56 PM Although M&K brought in a tunnel machine for the Thistle tunnels, the rock quality was such that the tunnels were drilled using conventional techniques. There was no shortage of labor around as the coal mines in the area were mostly shut down until the tunnel was opened. The first train went through within hours of holing through as the tunnel was dug full size. Then M&K made DRGW an offer they could not refuse for the second bore. The second bore was also drilled using conventional techniques, but was fully lined before use. Then traffic was diverted to the second bore while the rough bore #1 was lined and the track brought up to mainline standards.
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Deggesty
| Posted by Deggesty on Monday, May 18, 2009 10:11 PM For information on the Hoosac Tunnel, you can check www.hoosactunnel.netIt gives the history of the construction and much more information ( I barely looked at the site before posting this). Johnny Johnny
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erikem
| Posted by erikem on Monday, May 18, 2009 11:07 PM
There's a nice write-up in Middleton's When the Steam Railroads Electrified, both the original Kalmbach edition and the Indiana University edition. There's also a short article in CERA's bulletin #118, Westinghouse Electric Railway Transportation.
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Bruce Kelly
| Posted by Bruce Kelly on Tuesday, May 19, 2009 12:26 AM LV's original tunnel under Musconetcong Mountain at Bellewood (now Pattenberg), NJ, was doubletracked. Later reduced to single track to accommodate modernized equipment size in the 1920s, then replaced by a larger, adjacent doubletracked tunnel. (To see the original tunnel now, it's hard to imagine anything of reasonable size could have fit through there on two parallel tracks.) State Line Tunnels just west of the NY/MASS border had two tracks in the original north bore (1840s) and two more in the subsequent south bore (1912), both later single tracked to accommodate modern equipment and the north bore eventually taken out of service. Then there are those dual tunnels along the east shore of the Hudson River which at one time had doubletracked tunnel next to doubletracked tunnel as well as doubletracked tunnel next to single-tracked tunnel. And let's not forget the doubletracked Sand Patch Tunnel which replacedB&O's original single-track tunnel under the Alleghenies, Otisville Tunnel which replaced Erie's original line which looped up and over the Shawangunk Mountains, and otherlesser-known doubletracked tunnels such as the LV's Rockport Tunnel in the Lehigh Gorge.
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Tuesday, May 19, 2009 4:23 AM There's also a double-track tunnel - about 3,000 ft. long as I recall, when we hiked through it about 40+ years ago- to the south (railroad east) of the Tunkhannock Viaduct at Nicholson, Penn. on the former DL&W - now CP. But that one was also drilled as part of the separate project for the realignment and improvements early in the 20th century, not "under traffic". - PDN. EDIT: Scaled and taken from Google Maps: About 3,500 ft. long; about 2 miles south of town = intersection of U.S. 11 = Lackawanna Trail with PA 92 = Bacon St. and Grand Army of the Republic Highway. The NW portal is about 1/4 mile SE of Rt. 11 along the "Abington and Waterford Turnpike Rd.", down the hill on the NE side. For the SE portal, continue SE on the Turnpike Rd.about another 1/2 mile (it may turn into "College Ave.") to Tunnel Rd. on the NE side; go NE about 0.1 mile, and the portal will be down the hill a ways on the right = SE side, before the intersection with Spencer Hill Rd. "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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jchnhtfd
| Posted by jchnhtfd on Tuesday, May 19, 2009 8:51 AM There is another reason for two single bores (sometimes with a pilot bore in between) in modern tunneling practice (such as the Gotthard base level tunnel, and the Channel tunnel): safety. If you have two bores side by side, say a few metres apart, you can (and do) have interconnecting little tunnels between them, with fire doors on them. Then is something goes seriously wrong in one bore -- say a truck on a flat car catches fire (it's happened) or something like that -- it is possible for all and sundry in the one bore to go to one of the cross connecting tunnels and get into the other tunnel or the pilot bore (left open for that reason), close the fire door, and wait for the cavalry to show up... Jamie
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Bruce Kelly
| Posted by Bruce Kelly on Tuesday, May 19, 2009 8:55 AM You're referrring to Factoryville Tunnel (aka Nicholson Tunnel). DL&W's original single-track tunnel through that mountain was completed 1854. A second, parallel, single-track tunnel was completed 1883. Both were replaced by the current double-track tunnel in 1915, which has since been reduced to single track. I rode an NYS&W business special through there about 20 years ago, and the dome car enabled a great view of the cavernous ventilation shaft(s)which rose up through the tunnel ceiling to the surface. It's one of several double-tracked tunnels the DL&W built during a period when certain American railroads were emulating the high engineering standards of their better-financed European counterparts.
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henry6
| Posted by henry6 on Tuesday, May 19, 2009 9:22 AM
Also note there are two different alignments...the old pair about a mile from the new tunnel and about a hundred feet in elevation, too RIDEWITHMEHENRY is the name for our almost monthly day of riding trains and transit in either the NYCity or Philadelphia areas including all commuter lines, Amtrak, subways, light rail and trolleys, bus and ferries when warranted. No fees, just let us know you want to join the ride and pay your fares. Ask to be on our email list or find us on FB as RIDEWITHMEHENRY (all caps) to get descriptions of each outing.
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Tuesday, May 19, 2009 9:28 AM
Bruce, for a western guy you have a surprising - and embarassingly ! - good knowledge of eastern railroad tunnels. Your reference to the Hudson River tunnels had me puzzled for a little while - then I figured out you probably meant the Cold Spring, NYtunnels, which are actually about 2 miles north of that town, on the former NYC main line, and about 500 ft. long. (Cold Spring is basically on the other side of the Hudson River and about 2 or 3 miles north fromthe U.S. Military Academy at West Point.) There appear to be a similar tunnel(s ?)about 350 or 400 ft. long, 5 or 6 miles further south (south of Manitou) under the Bear Mountain Bridge (U.S. Routes 6 and 202) across the Hudson River. There also appear to be other(s) about 350 ft. long about 3/4 mile further south, and yetanother one (or 2 ?) only about 70 ft. long about another 3/4mile further south as well. Pattenburg Tunnel is about 4,800 ft. long. Rockport (another one I hiked through about 40+ years ago) is about 1,500 ft. long. Otisville looks to be only about 1,000 or 1,200 ft. long. I'm not sure about how long B&A's State Line Tunnel or the B&O's Sand Patch Tunnels are - but my general recollection is a couple thousand feet at most. Other than the Hoosac Tunnel (almost 5 miles - which was drilled as a double-track, too, but that took almost 25 years !), I can't recall an above-water tunnel in the NorthEast U.S. that's much over a mile long. There may be a few of that length further south in former N&Wand Clinchfield territory, but not many. All of which is to say that enlarging a "live" single track tunnel "under traffic" to a double track tunnel is surely not easy, but for short tunnels such as these not as difficult as for the typically longer western tunnels. Keep in mind too the traffic pattern for a single-track tunnel back in the day - comparatively long intervals between some of the trains so that the opposing moves can meet and pass each other at the next passing siding or double track on either side. On the other hand, that may be happening just a few feet beyond the portal ! Nevertheless, the access and logistics are far more manageable for a tunnel that's only 800 ft. or so max. from each portal, as compared to one that might be several thousand feet. - Paul North. "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Bruce Kelly
| Posted by Bruce Kelly on Tuesday, May 19, 2009 9:57 AM Paul, were it not for my nearly eight years (1988-1996) living in northern New Jersey, when I was associate editor of Railfan & Railroad, I might never have learned much about nor gained an appreciation for Eastern railroads. Well, I did get an early taste when we flew from California to Buffalo in the late 1970s to visit my mother's parents, aunts, uncles, and cousins in Attica, NY. (None of them residing in the infamous prison there, though one uncle did work there.) Still have some nice color negs of D&H, EL, LV and other power working the hills on either side of town, including helpers.Some articles published around that period, Bill Rettburg's Sand Patch piece in Trains and just about anything Nelligan, Hartley, or Bachman did from New England, really captivated me when I was living less than an hour from places like the Surf Line, Cajon, or Beaumont Hill.As for those Hudson River tunnels, you listed them pretty well. I should have framed them with the State Line Tunnels under a heading that emphasizes their noteworthiness for combining BOTH of the tunnel styles this thread is talking about: side-by-side AND double-tracked tunnels.
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Modelcar
| Posted by Modelcar on Tuesday, May 19, 2009 10:01 AM .....Don't forget the Allegheny tunnel...{one of twin tunnels}, on the ex. Pennsylvania RR at Gallitzin, Pa. It has been modified to accept higher double stack consists and double tracked at the same time. This occured back about 1995. 2nd "double tunnel" {Gallitizin}, is now out of service since Allegheny was enlarged to double track. Tunnel lengths are about 3600'. Location at just above 2,100' elevation to slice thru the upper portion of the Alleghenies above Horseshoe Curve...westbound. Quentin
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Tuesday, May 19, 2009 10:26 AM Quentin, thanks for that. I hadn't forgotten the Gallitzin Summit tunnels, but as you know there have been so many changes there over the years that I wasn't sure of my recollection of the facts, and didn't want to mis-state them. You've obviously got themhandy to fill that omission.
*Ken did that as a sport in track in high school and college, so he claimed to know what he was doing. Evidently he did, because he was successful. He didn't jump back, though, because he wanted to prove to the skeptics and those of our club who were too afraid to go out to witness it that he had actually done it by coming back on a different arch than the one he went out on. - Paul North. "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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and "stupid-teenager-tricks" warning: Somewhat off-thread, but this most of this NorthEastern U.S. railfan audience will appreciate it: Someday soon (maybe later this summer ?) I'll scare you guys to death when I dig out, scan, and post my one-of-a-kind Kodacolor 620 (?) print from about April 1967 of Ken Wolfgang* broad-jumping between a pair of thoseparallel concrete arches of/ underthe Tunkhannock/ Nicholson Viaduct. It was at the northernmost full span - and for those of you who don't know - about 240 ft. above the ground below. Each arch is basically directly under 1 of the tracks, and there is a gap of - what, ?say, about 8 ft. apart - between each arch. I still getshivers when Ithink about it. 
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Modelcar
| Posted by Modelcar on Tuesday, May 19, 2009 10:35 AM ....Wow.....what is the value of life to some people....! Quentin
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henry6
| Posted by henry6 on Tuesday, May 19, 2009 11:18 AM
ERRRRAAAAAHHHHHHHHEEEEEEEEEEE! I know those arches and I haven't even seen the pictures yet! RIDEWITHMEHENRY is the name for our almost monthly day of riding trains and transit in either the NYCity or Philadelphia areas including all commuter lines, Amtrak, subways, light rail and trolleys, bus and ferries when warranted. No fees, just let us know you want to join the ride and pay your fares. Ask to be on our email list or find us on FB as RIDEWITHMEHENRY (all caps) to get descriptions of each outing.
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Tuesday, May 19, 2009 2:32 PM
I second erikem's recommendation of the chapter in the Middleton book. Also, the definitive book on it, "A Pinpoint of Light", thoughI don't recall if that is limitedto the drilling of the tunnel or goes on to include the electrification. Itshould be available from: North Adams Historical Society/ North Adams Museum of Historyand Science at: http://www.geocities.com/northadamshistory/index.html Perhaps a Boston & Maine Historical Society (if there is such a thing) would know of some other references. Finally, from a search of the "Index of Magazines" at the bottom of this page for KeyWord "Hoosac" - although I've not seen any of these, so I can't say if they cover the electric operation or not: "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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blue streak 1
| Posted by blue streak 1 on Tuesday, May 19, 2009 11:10 PM PDN: Bremer Austria is going to let a contract very soonfor building two new separate (lower)tunnels. One thing about the contract that Mudchicken and RWM will like is the pilot tunnel will be built about 10 meters lower than the operating tunnels and be used for drainage. Water in tunnels - be gone. Tunnels will have the usual predestrian cross over passages and two interlockings in tunnels.
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jclass
| Posted by jclass on Tuesday, May 19, 2009 11:16 PM
Thanks erikem and Paul.
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Paul_D_North_Jr
| Posted by Paul_D_North_Jr on Wednesday, May 20, 2009 5:17 AM The article in the June 1960 Trains has very little on the electrification - only about 2 short paragraphs - not worth pursuing, in my opinion. The 1947 article by F. H. Cramer may be the same Forman H. Cramer, who wrote the nice article about the DL&W tri-power "Kiddie Kar" locomotives in the 1960s or 1970s. He was a GE engineer, and so that article would likely be worth looking for. My 1974 copy of Middleton's book has the segment on the Hoosac Tunnel electrification in the"Taming the Tunnels" chapter, pp. 148 - 153 inclusive, plus a short summary paragraph and location sketch on pg. 428. He does not cite anyspecific references for any of it - only journals and books generally in the introduction. - Paul North. "This Fascinating Railroad Business" (title of 1943 book by Robert Selph Henry of the AAR)
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Modelcar
| Posted by Modelcar on Wednesday, May 20, 2009 10:29 AM
That design sounds effective....I have wondered how much effort is required to keep the Chunnel {double tunnels}, free of leaking water.... One would assume it has to be pumped out, and that means pumping water for miles and miles in distance, and up grade too..... Quentin
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