Helixes, Tunnels, Spirals, and Other Unique Trackage

Most of us know what a helix is. In fact, I would guess that many of us have seen one in a model railroad layout, sometimes hidden in a mountain. But how prototypical are they? Is there such a thing as a full size standard gauge helix? What about other trackage commonly found in model railroads such as loops, crossovers, tunnels, etc. Most modelers find a way to incorporate at least one of these into their layout. Some modelers may go to great lengths to make sure their rolling stock is prototypical. Do they have a double standard by using trackage of this sort? The answer is: "Well, perhaps not..."

Some of you may be surprised to hear that one can find examples of all of this trackage in real life. The purpose of this article is to show you where odd trackage like this is used on real, full scale railroads.

Much of the information contained in this article was generated by railroad enthusiasts discussing this very topic on a computer network called USENET. I have collected, re-written and assembled this information into what you will see here. While I have found that there is interesting trackage all over the world, most of this article (except for "helixes") will concentrate on what can be found in the United States and Canada.

Perhaps the most interesting of all trackage in a model layout is the helix. If you consider that one revolution of a helix is a loop, you will probably realize that in real life there are a number of famous "helixes" including Tehachapi Loop. Can this be considered a helix? Well, maybe. There are many more examples to consider.

North American Examples

One of the most interesting of such tunnels with loops is right here in North America. It is in Canada and is called "Kicking Horse Pass". It is on the CP main just east of Field, B.C. in the Western Canadian Rockies. It is a series of two tunnel/spirals. The tunnel under Cathedral mountain is 3255 feet long with a turn of 291 degrees, and the one under Mount Ogden turns through 217 degrees over 2992 feet. The ruling grade is 2.2%. The tunnels were completed in August 1909, and replaced the route up the "Big Hill", which had a 4.5% grade. There is a lookout just off the Trans-Canada Highway from which you could observe both portals of the tunnel. Passengers can ride this route, at least in the summer, on Great Canadian Railtours' "Rocky Mountaineer" train from Calgary to Vancouver.

Here is a simple picture showing the general layout.

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One amazing piece of trivia about their construction is that when they bored these tunnels, they were off on one tunnel by 1 and 1/2 feet when the two ends connected, and 6 inches on the other. Not bad for the technology back then!

There is also a loop on the Bonavista Branch (3'6" gauge) in Newfoundland. It is called the "Trinity Loop". It has been preserved and is the site of a railway park called - The Trinity Loop Park. Some of the narrow gauge Equipment that was used on the Bonivista Branch of the Newfoundland railway is on display and train rides around the loop are available.

Iowa/Illinois Tunnel-Bridge:
There is a tunnel at Dubuque, Iowa (rather, in Illinois on the other side of the Mississippi.

Dubuque is in a deep valley (by mid-western standards), and in that particular part of the valley, the Mississippi is hard against the limestone bluffs on the east side of the valley, making space for the city of Dubuque on the west bottom land of the valley.

The Burlington mainline runs up the east riverbank, squeezed tightly between the river and the limestone cliffs.

Puzzle? How do you build a bridge across the river from the Burlington to Dubuque? There's no room for a rail yard on the East bank, and the port of Dubuque was and still is a big commercial operation.

Answer, build the bridge straight across the river, then tunnel into the cliff for a fairly sharp curve. Here's an attempt at ASCII graphics showing how it works:

                              /               \
         track in tunnel --> /                 \
                            /                   \
                           |                     \
                           |                      \junction
                          -|-                               ^
                          -|-                               |
                          -|-                               |- Double Track Main
    Mississippi           -|-
       River              -|-
                          -|-  <--- CC&P Bridge to Dubuque
Note that the bridge is a swing bridge, and that the swing span is at the east bank because the deepest part of the river's channel is right against the bluffs. If the swing span were on the other side of the river, a curved trestle could have been built out from the junction into the river, but it isn't easy to put a curve on a movable bridge span.

In the USA, there are a number of spirals (not in tunnels) in service:

Tehachapi Loop:
This trackage is east of Bakersfield CA on track shared by the SP & ATSF. Tehachapi is freight-only with very heavy traffic, and can be viewed effectively from a car.
Hiwassee Loop:
This loop is on CSX (former L&N) trackage between Copper Hill and Etowah TN. Hiwassee would be the most spectacular if it weren't for all the trees in the area (it goes around the mountain twice).
Georgetown Loop:
This is part of a tourist railroad. The loop includes a rebuilt bridge over the "Devils Gate Viaduct". This line is the former Colorado Central narrow gauge. Georgetown passenger trains are usually pulled by Shays.
Williams Loop:
Williams Loop is on the Union Pacific (former Western Pacific Feather River Route) not far from Keddie, CA. The track winds around a broad valley and crosses over itself (on a short bridge). It is a good photo spot, but hard to shoot in its entirety due to the heavy tree cover in some areas.
Roaring Camp:
The Roaring Camp and Big Trees Narrow Gauge Railroad is in Felton, CA. In Spring Canyon there was a tight spiral with a trestle over a another trestle. Sometime in 1976 an arsonist burned the trestles. A steep switchback was quickly substituted in its place. The remains of the trestle still stand. You can walk down from the summit of the hill, and follow the path that the trains used to take.
Thebes, IL:
Although no longer existing today, there was some very interesting trackage centered in Thebes, Il. This trackage included the Missouri Pacific main, the Illinois Central "Mud Line" (named because of frequent flooding), and the Chicago & Eastern Illinois. The IC and C&EI had a wye which led to the MP. The entire trackage had a loop in it.

It seems rather odd from a 1990's context that an out-of-the-way town like Thebes could be such a focal point for so many lines. But in the days when bridges over the Mississippi were few and far between, Thebes (and Cairo as well) assumed importance as locations where freight and passengers were ferried over the Mississippi.

As time passed, Thebes' importance dwindled. IC's line south to Cairo was pulled up during the Depression since alternate routes were available. The remainder of IC's "Mud Line" from Murphysboro was abandoned in the 1960's as far north as the power station in Grand Tower. MP gained control of the C&EI in the mid-1960's and, having numerous better routes from Chicago, downgraded and eventually abandoned the old C&EI main. Likewise, as Cairo's significance dwindled, the MP line from Thebes to Cairo was taken out of service in the seventies.

All that remains in Thebes is the MP's high-speed Chester Sub, now owned by Union Pacific and used by UP and SP (Cotton Belt) under the joint track arrangement.

Rifle Sight Notch, Colorado
The upper trestle, built directly over the lower tunnel is located at Rifle Sight Notch in Colorado. It is on the original Denver, Northwestern, and Pacific Railroad, built by David H. Moffat Jr. beginning in 1902 (actual construction over the Continental Divide was in the summer of 1903). He ended his first year of construction just a few miles past his loop. He used this loop design in his plan of the descent from Rollins Pass (11,680 ft. above sea level). Roadbed construction proceded west over the Divide and ran parallel to the Divide for several miles until it reached a course of descent to lower the line into the Fraser River Valley. Moffat began his decent down from the above tree line course he was on, he needed a 200 foot drop to hold at a steady 4% grade or descent. The loop around the small peak located just away from the main range, gave the road its steady 4% grade. The tunnel under the trestle caved in many years ago but the portals are or were still there in 1984. The trestle above is in ruins and not safe to crawl across as most of the cross ties are gone. A rough gravel road bed which can be negotiated with 2 wheel drive although it doesn't go all the way over any more.
  • Photo 1 (photo from "The Giants Ladder" by Harold A. Boner)
  • Photo 2 (photo from "The Giants Ladder" by Harold A. Boner)

In other parts of the world there are a number of tunnels with helixes or loops in them!

There are two spirals in New South Wales. One, at Border Loop going into Queensland, is a "standard" spiral, albeit with an extra tunnel which is not required as part of the tracks-crossing-over-themselves function. Here is a google map view of the loop.

The other at Bethungra (near Junee) is more unusual, because the spiral is on only one of two tracks in a double-track route. The downhill track is direct, but the uphill track passes over and under not only itself but the downhill track as well. At one point, there are three "layers" visible along the side of the hill: the uppermost part of the uphill track, then the downhill track in the middle, then the lower part of the uphill track. This link should bring up a map showing its location.

In Bulgaria there is such a tunnel on the Sofia - Karnobat - Varna/Burgas line. The single-track tunnel is situated at about 150 km east of Sofia and is 4 or 5 km long. The eastern entrance is at about 100 meters under the western one and the line continues from the western end over a viaduct that crosses both the valley and the track east from the tunnel (you can actually see the lower entrance of the tunnel from the viaduct).
There is an example of a loop track (in a tunnel) right inside the city of Rijeka, Croatia. It was built between WW1 and WW2 when the city was divided between Italy and then Yugoslavia. This was done in order to provide rail connection to the main line Rijeka-Zagreb from the new rail Susak station built in the eastern part of the city.
The "Piggy's Tail Railway Line" in the south of Badian, Germany extends 25.8 kilometers from Weizen up to Zollhaus-Blumberg. It was built in the 1880s for military (strategic) reasons and taken out of service in 1955 by the Deutsche Bundesbahn but not withdrawn. Today (since 1977) it is a well known museum-railway line with steam-locomotives in service.

The absolutely crazy trackage of this line represents the only spiral-tunnel in Germany. The length is 1700 meters and radius is 350 meters. Only a portion of the 360-degree spiral is inside a tunnel. The altitude gained by this full circle is 15.5 meters. The name of the tunnel is "Grosser Stockhalde-Kehrtunnel". About 60 meters of the tunnel contains straight track.

The idea of this trackage came from Mr. Robert Gerwig, famous constructor of the Schwarzwaldbahn (black-forest-line in Germany) and supporter of the Gotthard-line as well. The Wutach Valley line (another name for the Piggy's Tail Railway Line also has a 180-degree tunnel (called "Weiler Kehrtunnel").


Great Britain:
The best that Britain can manage is an open-air spiral on the Ffestiniog Railway in North Wales. This was built around 1970 as part of the diversion to complete the re-opening of the line to Blaenau Ffestiniog, the original route from Dduallt (or thereabouts) having been flooded by a hydro-electric reservoir.
The standard guage line from Bordighera to Cuneo up the Roya valley and over the pass above Tende has some wild engineering on the southern ascent including several spirals in tunnel. It isn't as well known as it might be. It was built by the Italians for strategic purposes and today the central part of the line is in France but running Italian trains. It is slightly disappointing to travel in as you emerge from the tunnels so briefly that all you hjave time to do is realise you haven't a clue where you are on the rock face before you plunge back into darkness again.
New Zealand:
The Rarimu spiral is located in the centre of the North Island of New Zealand. It climbs about 700 feet in 5 miles and has two loops over itself.
In Norway, on the line from Oslo to Bergen, you go over a pass at about 2600 meters, and at or near the summit pass through a town called Myrdal. There exists a local rail line that goes down the mountain from Myrdal to Flam, dropping from the 865 meter elevation to almost sea level in a very short 15 kilometers or so, by using two complete helixes bored through solid rock, you get a view out about half way down before finally exiting in a valley far below the beginning point at Myrdal. The line is electrified, and it is a very noisy ride down through the tunnel (with the brakes and dynamic braking used to control the train decent). I do not have much on the actual grades etc, but know there is more info on the web under eurail or scanrail pass sites. Information provided by Brent Andersen.
In Switzerland there are double loops on both sides of the Gotthard. The old Furka Oberalp cogwheel line also has a steep helix tunnel at 8% grade and minimum radius on top of which the highway makes a hairpin turn.

The Gotthard tunnels are on the northern approach to the long tunnel between Goeschenen on the north and Airolo on the south. On the southern approach there are four spirals: two close together, curving in the same direction, and two, separated by a mile or two, curving in opposite directions.

One of the most famous loops is on the south side of the RhB Bernina line (1 meter gauge): a 360 degree spiral viaduct, not in a tunnel but in the middle of a valley, near Brusio:
  ,-.     |  /|\ (up) To Poschiavo - Bernina - St. Moritz 
 /   \    |   |
|     |   |
 \    |  /
      |       |
      |      \|/ (doen) To Tirano
To get a good view you have to wander up one of the hills nearby. It looks especially good when a long train is rolling through.
There is also a 2 km long tunnel making a 180 degree turn (there are actually two parallel tunnels) between Predeal and Timisul de Sus on the Bucharest - Brasov line in Romania. The first tunnel was built in the 1880s, the other one in the 1940s when the line was doubled. The average rate of descent on the 10 km stretch from Predeal to Timisul de Sus is 3.0%, making this section the most "abrupt" mainline in Romania. The line was electrified in 1965; until then a 2,000 ton freight train had to be hauled at no more than 20km/h by 4 - 5 steam locomotives!
Another one is in Serbia, on the Belgrade - Bar line.

Besides "spirals" (or helixes) what other unusual track arrangements are worth mention? How about "Grand Unions"?

The CNJ had a "Grand Union" -- two lines intersecting (at 90 degrees in this case) with tracks connecting adjacent "arms". A train approaching the diamond on any of the four arms can proceed straight, left or right.
                               / | \
                              /  |  \
                              \  |  /
                               \ | /
Chicago Tunnel Company:
The CTC may have held the record for grand unions, among ICC regulated common carrier railroads. They had grand unions under most of the street intersections of the Chicago Loop district. Of course, it was all two foot gauge traction, using mine locomotives, but they had something like 50 miles of track.

The CTC tunnels, by the way, were the tunnels that were flooded last summer when someone drove a piling too close to one of the tunnels under the Chicago River and cracked the cement tunnel liner.

Odenton, MD:
According to the DeLorme Atlas&Gazetteer for Maryland/Delaware, there was a grand union in Odenton, MD.
JESSUP,MD                                 | | |
  ||                                     /| | |\     | industrial spur
  ||/                                   \ | | | /  ODENTON,MD
  ||                                     \| | |/
                                          | | |
B&O Washington Branch (2-track)         PRR (3-track (maybe 4)) 
                                        (now NEC)
Toronto Union Station:
The Canadian National Railways northward line to Barrie (from the Toronto Union Station) crosses (at grade) the main Toronto East-West bypass (which is double track) that goes into the CN marshaling yards (North of Toronto). The Northbound and Southbound trains can both be switched off to either Eastbound or Westbound.
Kansas City, MO:
Kansas City has a complete and active grand junction with two adjoining "almost grand junctions" all underneath an elevated wye with one leg passing underneath another, all connecting to a double-decked double-tracked elevating bridge.

Kansas City also has at least one other grand junction and a snarl of "air line junctions" and fly-overs.

Topeka, KS:
Topeka has the active remains of a grand junction and a wye junction connected by an elevating bridge.
Dalhart, TX:
Dalhart, TX has the active remains of Grand Junction with a four lane street passing underneath.
Rochester, NY
There is a grand union at the P&L Junction, south of Rochester, NY Where the Lehigh Valley Railroad crossed the Buffalo, Rochester & Pittsburg railroad. map

Reversing loops are actually quite common. I'm sure there are more, but here is a list of at least some of them:

Bay Head, NJ:
On the NY&LB (CNJ/PRR) there is a reversing loop so that power did not have to be run around the train. What purpose does it serves now with push-pull trains? A conductor on the Bay Head train said: "Well they only have to flip the seats at the Long Branch end of the shuttle."
Grand Central Terminal:
More well known are the reversing loops under Grand Central Terminal (NYC). One reason for these is that long-distance trains got cleaned and prepared at Mott Haven, the Bronx, just north of Manhattan. Incoming trains discharged passengers at the arrivals platforms at the west side, and then could run forwards around the loop to go to Mott Haven. This doesn't really explain the loop on the suburban level, which possibly was used to reduce conflicting train movements at least for the trains that looped. A loop terminal is more efficient than a stub terminal since with a loop you shouldn't have to have outbound and inbound trains crossing.
Harmon, NY:
There are the remains of an overhead reversing loop at Harmon, NY on the NYC just north of the shops. This loop crossed over the main line. All that remains now are track supporting structures. The old Harmon loop now serves as a means to access a condominium project they placed on the river.
Sunnyside, NY:
There is a loop at Sunnyside Yard that goes under the main just west of Harold tower. The yard is on the north side of the main tracks that run to New England and to the Long Island RR. Trains from Penn Station use the loop to pass under the main tracks and enter the yard from the east or far end. When leaving the yard, they run out the west end. This is a very nice arrangement as all trains in the yard face the same way (west/south); the loop serves both to cross the main and to reverse the trains.
Quite a few of the narrow gauge railroads in Colorado had reversing loops. Why did they construct loops instead of a wye or turntable? The reason is because it was necessary to turn snow plows. A turntable would have been too short for an engine and a snowplow. A wye would not work because it would require that the snowplow be pulled backwards through snow for part of the turning operation.
Cumbres & Toltec:
There are actually two loops on the ex-D&RGW narrow gauge that now make up the 64 miles long Cumbres and Toltec Scenic RR. The first is at Lava tank (which is 8-10 miles out of the eastern terminal of Antonito), and this was for turning the rotaries snow plows and sending them back towards Cumbres. The second loop (isn't actually completed yet) is located east of Osier and will allow the train sets from Chama to be turned with a minimum of effort.

The D&RGW usually plowed west from Alamosa and DOWN the 4% grade into Chama, but if the present-day C&TS needs to clear Cumbres pass, they need to plow UP the 4% grade which necessitates at least 2 engines. While there was a snow shed on one leg of the wye at Cumbres, it is actually on the wrong leg when a rotary was coming from Chama. If anybody was present in 1991 when the C&TS ran the rotary OY, they realized that other methods were needed to plow that 3rd leg of the wye since they don't have any way to plow snow while backing up.

Val Royal:
There's one still in service at Val Royal on the CN electric commuter line NW of Montreal.
Colton Yard:
There's another (freight only) at SP's Colton Yard near San Bernardino, CA.
Rockport, MA:
There was also one at Rockport on the B&M - it faced the stub end of the branch so engines always backed around it.
Donner Pass:
The USGS maps for Donner Pass clearly show turning loops on either side of the pass -- for rotaries and flangers. One of the loops (west of Emigrant Gap) isn't level. They had to deal with the side of the mountain and it goes off into the woods and rises up probably 30-40 feet, and comes back down and enters the main line. Most people on the AMTRAK Zephyr probably don't realize what it is. Obviously it isn't used except in the worst conditions, so its doubtful you'll ever see of picture of it in use!
Moffat Loop:
There is a wye on the east side of the tunnel. There is a loop located at Tabernash, CO which is west of Frazer, CO several miles. The loop is quite large and includes a small yard and a wye inside
Stone Mountain:
The Stone Mountain RR (near Atlanta, GA) has a circle of track that circles Stone Mountain (the largest known single piece of granite in the world I believe) with a wye at one point which connects to the outside RR world (CSX or NS?). So we have a reversing loop and complete "loop" all in one.
Lambert's Point, Norfolk, VA:
Lambert's Point is where Coal Pier 6 is located, the end of the line for much of the coal hauled on the Norfolk & Western from West Virginia and Southwest Virginia. The track makes a wide circuit around the yard and gained some notoriety several years ago when the J-class 611 made its inaugural run. The train left Roanoke on a Saturday, headed east to Norfolk amidst great fanfare. After a overnight stay, the train was to return west to Roanoke on Sunday. The passengers did come west on Sunday, although the train was late a pulled by diesels. The J came back much later, tender first, and assisted by diesels. It seems that the track gauge had been tightened on the balloon track after the demise of steam on the N&W. When the J started around the balloon track to be turned for the return trip, the rigid wheelbase of four driving axles didn't agree with the tighter gauge of the reversing loop. After the J came near to derailing, the turning project was stopped and heads were scratched. It was determined that there was no way to turn the engine (the turntable in Norfolk had long since been removed), so the disappointed passengers got diesels and the J came back under slow orders, to the Roanoke turntable, the only known safe place to turn the engine (it was decided not to chance the engine on any of the several wyes between Norfolk and Roanoke). Soon after that embarrassment, the N&W did a system-wide check of its tracks to make sure they would accommodate the J in excursion service.
As you can see, there are plenty examples of exotic trackage. Perhaps the only difference between that found on the prototype railroad and that which is found in our model layouts is that:
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