Editing First transcontinental railroad (section)

===Central Pacific construction===
On January 8, 1863, Governor [[Leland Stanford]] ceremonially broke ground in Sacramento, California, to begin construction of the Central Pacific Railroad. After great initial progress along the Sacramento Valley, construction was slowed, first by the foothills of the [[Sierra Nevada (U.S.)|Sierra Nevada]], then by cutting a railroad bed up the mountains themselves. As they progressed higher in the mountains, winter snowstorms and a shortage of reliable labor compounded the problems. On January 7, 1865, a want ad for 5,000 laborers was placed in the Sacramento Union.<ref name="dobie">{{cite book |last1=Dobie |first1=Charles Caldwell |title=San Francisco's Chinatown; Chapter IV: Railroad Building |date=1936 |publisher=Appleton-Century Co |location=New York |pages=71–72}}</ref> Consequently, after a trial crew of [[Chinese Railroad Workers|Chinese]] workers was hired and found to work successfully, the Central Pacific expanded its efforts to hire more emigrant laborers—mostly Chinese. Emigrants from poverty stricken regions of China, many of which suffered from the strife of the [[Taiping Rebellion]], seemed to be more willing to tolerate the living and working conditions on the railroad construction, and progress on the railroad continued. The increasing necessity for tunneling as they proceeded up the mountains then began to slow progress of the line yet again.

[[File:CPRR Donner Summit Tunnel Hand Drilled Granite 1868.jpg|thumb|left|Example of hand-drilled granite from within Tunnel#6, the "Summit Tunnel"]]
The first step of construction was to survey the route and determine the locations where large excavations, tunnels and bridges would be needed. Crews could then start work in advance of the railroad reaching these locations. Supplies and workers were brought up to the work locations by wagon teams and work on several different sections proceeded simultaneously. One advantage of working on tunnels in winter was that tunnel work could often proceed since the work was nearly all "inside". Living quarters would have to be built outside and getting new supplies was difficult. Working and living in winter in the presence of snow slides and avalanches caused some deaths.<ref>Ambrose, Nothing Like It in the World, pp. 160, 201.</ref>

To carve a tunnel, one worker held a rock drill on the granite face while one to two other workers swung eighteen-pound sledgehammers to sequentially hit the drill which slowly advanced into the rock. Once the hole was about {{convert|10|in|cm}} deep, it would be filled with black powder, a fuse set and then ignited from a safe distance. Nitroglycerin, which had been invented less than two decades before the construction of the first transcontinental railroad, was used in relatively large quantities during its construction. This was especially true on the Central Pacific Railroad, which owned its own nitroglycerin plant to ensure it had a steady supply of the volatile explosive.<ref>Howard, Robert ''The Great Iron Trail.'' New York: G.P. Putnam's Sons, 1962. pg. 222</ref> This plant was operated by Chinese laborers as they were willing workers even under the most trying and dangerous of conditions.<ref>Howard, Robert ''The Great Iron Trail.'' New York: G.P. Putnam's Sons, 1962. pg.222</ref>

Chinese laborers were also crucial in the construction of 15 tunnels along the railroad's line through the Sierra Nevada mountains. These were about {{convert|32|ft|m}} high and {{convert|16|ft|m}} wide.<ref name="Tzu-Kuei p. 128">Tzu-Kuei, "Chinese Workers and the First Transcontinental Railroad of the United States of America", p. 128.</ref> When tunnels with vertical shafts were dug to increase construction speed, tunneling began in the middle of the tunnel and at both ends simultaneously. At first hand-powered [[derrick]]s were used to help remove loose rocks up the vertical shafts. These derricks were later replaced with steam hoists as work progressed. By using vertical shafts, four faces of the tunnel could be worked at the same time, two in the middle and one at each end. The average daily progress in some tunnels was only {{convert|0.85|ft|cm}} a day per face, which was very slow,<ref name="Tzu-Kuei p. 128"/> or {{convert|1.18|ft|cm}} daily according to historian George Kraus.{{r|"Kraus Chinese 1969"|p=49}} J. O. Wilder, a Central Pacific-Southern Pacific employee, commented that "The Chinese were as steady, hard-working a set of men as could be found. With the exception of a few whites at the west end of Tunnel No. 6, the laboring force was entirely composed of Chinamen with white foremen and a "boss/translator". A single foreman (often Irish) with a gang of 30 to 40 Chinese men generally constituted the force at work at each end of a tunnel; of these, 12 to 15 men worked on the heading, and the rest on the bottom, removing blasted material. When a gang was small or the men were needed elsewhere, the bottoms were worked with fewer men or stopped so as to keep the headings going."{{r|"Kraus Chinese 1969"|p=49}} The laborers usually worked three shifts of 8 hours each per day, while the foremen worked in two shifts of 12 hours each, managing the laborers.<ref>John R. Gillis, [http://cprr.org/Museum/Tunnels.html "Tunnels of the Pacific Railroad."] Van ''Nostrand's Eclectic Engineering Magazine'', January 5, 1870, pp. 418–423.</ref> Once out of the Sierra, construction was much easier and faster. Under the direction of construction superintendent James Harvey Strobridge,<ref>{{cite web |url=http://freepages.rootsweb.com/~npmelton/genealogy/alam-str.htm |title=James Harvey Strobridge |website=freepages.rootsweb.com |access-date=February 28, 2021}}</ref> Central Pacific track-laying crews set a record with {{convert|10|mi|56|ft}} of track laid in one day on April 28, 1869. Horace Hamilton Minkler, track foreman for the Central Pacific, laid the last rail and tie before the Last Spike was driven.

[[File:CPRR Snow Gallery at Crested Peak C.E. Watkins No. 252 1868.jpg|thumb|right|CPRR snow galleries allowed construction to continue in heavy snow (1868).]]In order to keep the CPRR's Sierra grade open during the winter months, beginning in 1867, {{convert|37|mi|km}} of massive wooden [[snow sheds]] and galleries were built between Blue Cañon and Truckee, covering cuts and other points where there was danger of avalanches. 2,500 men and six material trains were employed in this work, which was completed in 1869. The sheds were built with two sides and a steep peaked roof, mostly of locally cut hewn timber and round logs. Snow galleries had one side and a roof that sloped upward until it met the mountainside, thus permitting avalanches to slide over the galleries, some of which extended up the mountainside as much as {{convert|200|ft|m}}. Masonry walls such as the "Chinese Walls" at Donner Summit were built across canyons to prevent avalanches from striking the side of the vulnerable wooden construction.<ref>Galloway, C.E., John Debo ''The First Transcontinental Railroad''. New York: Simmons-Boardman, (1950). Ch. 7.</ref><ref>Cooper, Bruce C. [http://cprr.org/Museum/Sierra_Grade_8-2003/Donner_Pass-Summit_Tunnel/index.html "CPRR Summit Tunnel (#6), Tunnels #7 & #8, Snowsheds, "Chinese" Walls, Donner Trail, and Dutch Flat Donner – Lake Wagon Road at Donner Pass"] CPRR.org</ref><ref>[http://cprr.org/Museum/Sierra_Grade_8-2003/Period_Views/index.html#Cisco "Period construction images of snowsheds at Cisco and Donner Summit"] CPRR.org</ref> A few concrete sheds (mostly at crossovers) are still in use today.