Southwest Railroad History

ABANDONED GRADES

Abandoned grades are rail routes from which the tracks and ties have been salvaged.  Some are "rails-to-trails" such as the bridge over the Santa Clara River for the abandoned Southern Pacific Santa Barbara Branch (1887) (left) and some are simply "old railroad grades" such as the fill grade for the abandoned Randsburg Railroad (1898) (right).

 

BOLTED RAILS

Bolted rails are what most people think of as railroad tracks.  The rails come in sections that are bolted together with brackets (as opposed to welded tracks discussed below).  When a train runs on bolted track, the train makes the iconic "clink-clink, clink-clink" sound as it rolls over the rail joints.  All railroads, except the most recent ones (late 1900's) were originally built with bolted track, but the active mainlines have almost universally been upgraded to welded track.  Bolted rails are still a common sight on branch lines.

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WELDED RAILS

Modern railways use continuous welded rail, sometimes referred to as ribbon rails. In this form of track, the rails come in sections up to a mile long and the joints are inconspicuous welds to form a continuous rail with no joints. This form of track is very strong, gives a smooth ride (no clink-clink, clink-clink), and needs less maintenance than bolted rails; trains can travel on it at higher speeds and with less friction.  The first welded track was used in Germany in 1924 and in the US in 1930 and has become common on mainlines since the 1950's.  The left photo is lower grade welded track, because it has spikes and wooden ties.  The photo on the right is the good stuff, welded track with concrete ties and clips instead of spikes.

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CUTS AND TUNNELS, FILLS AND BRIDGES

Railroads require gentle grades and wide curves, much more than for autombiles.  Railroad grades are generally lower than 1%; 2% is a maximum grade for modern routes over mountains, and grades of 3-4% are the maximum reached in the early mountain railroads.  To maintain the low and steady grade, routes are chosen to follow river valleys or at least to cross flat areas.  However, all routes must cross local topographic low points that must be brought up to grade and topographic high points that must be brought down to grade. The simplest way to bring up the grade is with earth fill (upper left photo). However, some topographic lows are so low that the amount of earth that must be moved to fill up to the grade is more costly than a bridge (upper right photo). By contrast, the simplest way to bring down the grade is an earth cut (lower left photo). However, some topographic highs are so high that the amount of earth that must be moved to bring down the grade is cost-prohibitive compared to a tunnel (lower right photo).  

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SWITCHES, SIDINGS AND WYES

Switches allow tracks to have junctions.  Without switches, trains would only be able to run from point A to point B on a single track. Switches use a lever that moves the converging tracks a few inches to allow trains to roll from one track to either of two tracks (upper left photo).  A single switch is all that is needed for a "siding," a track laid parallel to the mainline (upper right photo).  Sidings are necessary to allow trains to run in both directions on a single track; one train pulls onto a siding to let the other train travelling in the opposite direction to pass.  Multiple sidings are used in railroad yards to classify rolling stock and put together trains.  Sidings are also used for loading of freight and passengers.

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A switch would be an adequate junction if trains ran equally well forward or backward; an approaching train from any direction could go onto either track at the junction as long as it doesn't need to turn around. However, to allow an engine to head in the direction it's moving (i.e. engine facing forward and at the front of the train) requires a "wye," which is three switches arranged in a triangle (lower left photo; the lower right photo is an abandoned wye).  Wyes have two uses.  One use is to connect to a branch line, which allows trains from any of the three directions to continue onto either of the other two tracks and continue heading in the direction the train is moving.  The other use is for turning engines, at the end of the line or to turn helper engines at the tops and bottoms of grades; turning wyes usually only exend far enough to turn the engine and tender. 

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TRACK GAUGES

Track "gauge" is the distance between the two rails.  Similar to other parts of the country and the world in the mid-1800's, the first railroads in the Southwest were very short lines that transported goods to local ports and warfs for sea transport.  None were connected to each other or to a rail network and were built to various gauges.  When the first American transcontinental line was completed in 1869, the Southwest railroads immediately settled on two gauges.  The Union Pacific-Central Pacific transcontinental was built to the "standard" gauge of 4 feet 8-1/2 inches (56.5 inches), which was based on the British standard railroad gauge, which in turn was based on the standard spacing of wagon wheels and ruts in Britain. However, there was demand for narrower gauges on branch lines because narrower gauges are less expensive to construct and operate than broader gauges, and because narrow gauge allows for tighter curves, which make narrower gauges easier to build in mountain areas.  Led by the Denver & Rio Grande Railroad in the Rockies, Southwest railroads settled on a standardized narrow gauge of 3 feet (36 inches). However, the D&RG and almost all the other narrow gauge lines built in the Southwest have been either converted to standard gauge or abandoned. The D&RG Farmington Branch (1902) is the only line in the Southwest that was converted from standard gauge to narrow gauge (when it became clear the D&RG San Juan Extension would never be converted to standard gauge).

 

The only remaining commercial narrow gauge line in the Southwest is the Imperial Gypsum (1922) line in southwestern California (upper photo).  Several narrow gauge heritage lines operate in the Southwest such the Shay powered Madera Sugar Pine Railroad (c1910), today delighting railfans as the Sugar Pine & Yosemite Mountain Railroad (middle photo).  The conversion from narrow to standard gauge often resulted in a period of dual-gauging, a third rail to allow rolling stock of both gauges to run on the same track.  Antonito, Colorado, where the D&RG's standard-gauging program of the 1890's ended, is the best place I know to see dual gauge track in the Southwest (lower photo).