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I had the same dumb question, Paul. I too found nothing but “…a city in central California”.
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After examining the maps of the Heartland corridor questions comes to mind.
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The extension from Columbus, Oh to Cincinatti makes sense since starting out containers will need sortiing to make a full train to CIN. However when the Canal is finished and there may be enough traffic to run a direct train(s) from Portsmouth - CIN will that route upgraded?
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With that in mind would NS eventually upgrade CIN - Chicago to reduce the requirement for Chicago traffic to go by Crestline? Anyone know how many miles that would save?/ ,
Daylighting a tunnel will usually require removal of a huge amount of overburden and rock. A single track tunnel is often only 16’ wide, but when considering its removal the engineer is more or less obliged to go with a modern roadbed section, including drainage ditches and the like, needing a width of something like 30’ at the bottom. A vertical rock face is a recipe for future trouble, so figure on a 0.25:1 slope. When you reach the original surface, say 40’ above track level, the width of excavation will now be 50’, and that’s only if it is competent rock all the way.
Assuming you can afford all the drilling and blasting to remove the rock, the next challenge is where to put the waste material, perhaps a million cubic yards of it. It can’t just be dumped into the local valley because it will dam the river so it has to be hauled away to some other site. The railroad may have a suitable site with a big fill and plans to build a second track, but probably track time is not available to load and haul it by train. It’s going to take an awful lot of truckloads if part of the haul is on public roads.
Daylighting is sometimes the only option when a tunnel becomes dangerously unstable due to ground conditions. It can be the better option when double tracking, since boring a new tunnel for the second track may be just as expensive. (In general trying to widen an existing bore for a second track is not a good idea, although no doubt it has been done.)
Essentially, daylighting a tunnel is going to be a major expense, and there are usually more urgent priorities for the capital.
John
Daylighting a tunnel in many cases, is not practically possible. Locations with such a cover elevation that would not even be considered to such a change.
Yes, it’s the same tunnel.
When I have an opportunity, I’ll post a photo or two of mine from last April or so of the Gwynedd Cut, formerly the Gwynedd Tunnel, of the Reading RR - now SEPTA, about a mile southwest of the Borough of North Wales, PA - at Lat. / Long. N 40.19674, W 75.26733 per the "ACME Mapper 2.0 " application.
It was a shallow tunnel - well less than 100 ft. cover - when first bored through loose sedimentary rock in the mid-1800’s as part of the construction of the North Pennsylvania Railroad/ branch, but was ‘daylighted’ circa 1930 as part of the electrification of the Reading’s suburban lines to provide sufficient overhead clearance for the catenary wires and high-voltage transmission poles above. Recently SEPTA was installing chain-link fencing and shot-creting/ ‘guniting’ portions of the sides of the resulting cut to reduce the incidence and extent of the rockfalls, esp. during freeze-thaw cycles, and that’s when I took my photos one evening. It’s a good illustration of the points made by several other posts above about rock competency, groundwater effects, and by cx500 about how a cut should and must be wider than the tunnel it replaces. (As a philosophical aside, that may be another instance of the iro
In 1885 there certainly were mechanical excavators of the Steam Powered, rail mounted variety, and their largest application during that period was R.R construction…but you’re right, there was nothing like the modern, diesel powered and hydraulically driven monsters the construction industry uses nowadays…
I always marvel at what was accomplished by the early railcar mounted,steam shovels, steam drills ect. considering that a contractor had to lay temporary track by hand labor just to get the machinery into position to work…think of the Panama Canal…
One of the wonders of the line I volunteer on is that the 100 or so miles it ran were completed in about a year and a half, through some pretty rugged terrain (the Adirondacks), in 1891 and 1892. Most of the cuts (there are no tunnels) appear to have been done with “opportunistic” blasting - find a crack and stuff some dynamite in it. I have yet to see a drill mark.
Indeed - pretty amazing.
Oh, there probably were holes drilled for blasting in those cuts, Larry - maybe still by hand, perhaps air-powered, which by then had been proven and perfected just a few years before a few dozen miles away to the southeast over at the Hoosac Tunnel project. But those holes were so expensive to drill that the bare minimum number were used - and the dynamite used was so powerful and uncontrolled by our standards that it obliterated all traces of the drill marks. Any hole that was drilled got stuffed with the maximum amount of dynamite that it could hold, and of course it was all detonated as a single collective charge. Think about it a little bit - what would you expect to remain of the hard-rock side of a drill hole that was placed right next to a dynamite charge powerful enough to fracture the rest of the rock for at least a couple yards in each direction ?
- Paul North.
For those who do not think the rotten rock over burden can be disastorous just look at the Nc I-40 incident.
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NC DOT built the west bound lanes of I-40 near the Tennessee line with a tunnel for the west bound lanes only.
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To save money NC DOT shortened the east side of the tunnel about 500 ft from original plan so the approaches ended up under “bad” rock allowing the approaches to suffer constant rock falls that were easily controlled as NC DOT predicted.
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BUT finally the “bad” rock let loose and burried both east and west bound under over 10M + tons of rock. It took NC DOT 8 months to remove the rock (had to be trucked some distance), shore up the approaches, rebuild the road bed (east bound torn up worse than west bound don’t know why), install slide detectors and repave the road.
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I’ll admit that 8 months seems unreasonable even for a state agency. But even a RR would have had problems with that area as SOU RR has had. Its almost all shale rock in that location.
I wonder if anyone has some photos of that incident {I-40}, disastrous rock slide burying the interstate route. I have traveled thru there several times and was always glad when it was behind me.
Selected photos below. Commentary later when I have more time. Enjoy ! - PDN.
In addition to the technological limits of the time you also have to consider the state of the railroad busines back then. Since obviously things like Double Stack Intermodal trains, Autoracks, and Superliner passenger cars didn’t exist yet and nobody fathomed of their existence they figured that as long as it provides clearance for the equipment around at the time no sense going to all the extra work.
Consider the ‘grand-daddy’ of all tunnel ‘day-lighting’ projects - the Southern Rwy.'s gradual elimination of all but 1 tunnel on the former ‘Rathole’ division of the Cincinnatti, New Orleans & Texas Pacific / Cincinnatti Southern line, which is described in this article from the Southern’s “Ties” magazine titled "90 Years to “Daylight” ": http://southern.railfan.net/ties/1963/63-8/daylight.html
See also the messages on the forum about “Abandoned Rathole Tunnels” at this link: http://www.jreb.org/ns/index.php?topic=91.0
Finally, here’s a link to a recent Steve Schmollinger photo of the Kings Mountain Cut, which bypassed one of the early ‘Rathole’ tunnels (No. 1 ?) as part of the early 1960’s improvements. M-O-W people on other railroads that have cuts and tunnels to maintain have been known to cry ( [swg] ) when they see photos of cuts like this one - and the few new tunnels have almost as impressive overhead clearances:
http://www.railpictures.net/viewphoto.php?id=342451
- Paul North.