It was about this time in 1869 that a Central Pacific crew installed ten miles of new track in a day (the historical marker reads "laid in a day" but in reality there was ten miles of new rail in place if not properly surfaced, aligned and ballasted yet). One might suspect that the track-laying accomplishment was an artifact of geography, it being easier to lay a relatively straight track across relatively flat ground in Utah, rather than tackling the curves and grades in the Sierra.
A recent Trains article explains there was more at work.
In the beginning, Central Pacific were essentially assembling panels of snap track (to use a model railroading term) in place and finishing each panel before moving on to the next panel. Each panel was held in alignment with adjacent panels by a large rail joiner called a chair spiked to a tie with a special notch deep enough for the chair. Thus the two rails had joints opposite each other. It's something the British still do, on lightly-used lines, and bouncing along them in a nodding donkey is quite the experience. North American railroads went to staggered rail joints many years ago, after they discovered that having both ends of a heavily-loaded axle going over rail joints at the same time beat up the tracks.
To move rail's end on the Central Pacific forward involved hammering a chair onto the outer end of each of two rails, placing the notched cross-tie, placing the intermediate ties, hammering the inner end of each rail into the chair at the previous rail end, then spiking the chair into place and the rail to the intermediate tie. On curves, they'd pre-bend each section of rail (the inside and the outside) and cut the inside section so as to keep the joints square. Then repeat the procedure. It's a whole lot easier to open up a box of snap track; the factory has done this work for you.
A model railroader who works with flex-track has probably encountered the notched tie phenomenon. The tie strip on a piece of flex-track is supposed to hold the rail in place. There isn't room for a rail joiner, which means the builder has to substitute wood ties and spike at the joint.
After about seventy miles of struggling with chairs and curves, Central Pacific adopted a different method of joining rails at the end, with splice bars, and they kept a stock of rails six inches shorter than standard on hand, such that when the inside rail on a curve got six inches ahead of the outside, they'd attach a shorter rail at the next splice and press onward. But they were still building the track one panel at a time.
On Union Pacific, Jack Casement was getting several miles of track laid each day. Central Pacific management contemplated sending a spy to observe, but they didn't have to when an itinerant track hand working his way to California showed up just before the 1868 construction season began, looking for work.
Author Wendell W. Huffman explains what the track hand described at his job interview.
Casement achieved speed in tracklaying by involving more men, divided into specialized teams. While the traditional method involved a few men pitching in on every task in the limited area in front of the tracklaying car, Casement stretched the work space as long as possible. Ties were distributed from wagons well ahead of the rail laying, and the tracklaying car was rolled ahead on loose rails, allowing splicing and spiking to be done behind the car. Tie setters only set ties. Rail layers only laid rails. Splicers spliced and spikers spiked. Everyone gained proficiency.The tracklaying car is a small four-wheeled trolley that can be manhandled off the track when empty to make way for the next load coming to track's end. It had extra wide wheel treads in order to stay on rails that were not fully secured to all ties. The splicers and spikers are doing their work out of each other's way, behind the advancing tracks.
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