Editing Donner Pass (section)

==Central Pacific Railroad==
{{main|Central Pacific Railroad}}
[[File:Donner Pass Summit Tunnel West Portal.jpg|thumb|left|225px|alt=[PICT:Color of original long railroad tunnel]|''(Composite image with the tracks removed in 1993 digitally restored)'']]

In the spring of 1868, the [[Sierra Nevada (U.S.)|Sierra Nevada]] were finally overcome by the [[Central Pacific Railroad]] (CPRR), after almost three years of sustained drilling and blasting through granite by hundreds of Chinese workers,<ref>{{cite web |last1=Saxton |first1=Alexander |title=The Army of Canton in the High Sierra |url=https://www.jstor.org/stable/3636678 |publisher=Pacific Historical Review, Vol. 35, No. 2, pp. 141-152 |doi=10.2307/3636678 |date=May 1966}}</ref> with the successful completion at Donner Pass of its 1,659-foot (506 m) Tunnel #6 (a.k.a. the Summit Tunnel) and associated grade, thus permitting the establishment of commercial transportation ''en masse'' of passengers and freight over the Sierra for the first time. Following a route first surveyed and proposed by CPRR's original Chief Engineer, [[Theodore Judah|Theodore D. Judah]] (1826–1863), the construction of the four tunnels, several miles of snowsheds, and a hand-crafted stone retaining wall 75-foot tall (a.k.a. Chinese or China Wall in recognition of the Chinese builders) necessary to breach Donner Summit<ref>{{cite web|url=http://cprr.org/Museum/Sierra_Grade_8-2003/Donner_Pass-Summit_Tunnel/index.html|title=CPRR Summit Tunnel (#6), Tunnels #7 & #8, Snowsheds, Chinese Walls, Donner Trail, and Dutch Flat Donner – Lake Wagon Road at Donner Pass|publisher=Central Pacific Railroad Photographic History Museum|year=2014}}</ref> constituted the most difficult engineering and construction challenge of the original [[Sacramento]]–[[Ogden, Utah|Ogden]] CPRR route.<ref>{{cite journal|url=http://www.cprr.org/Museum/Tunnels.html |title=Tunnels of the Pacific Railroad|journal=Van Nostrand's Eclectic Engineering Magazine|volume=II|year=1870|pages=418–423|first=John R.|last=Gilliss}}</ref>
   
[[Image:Lmc tdj.jpg|thumb|right|225px|CPRR Engineers L. M. Clement and T. D. Judah]]

Principally designed and built under the personal, often on-site direction of CPRR's Chief Assistant Engineer, Lewis M. Clement (1837–1914),<ref>{{cite web|title=Lewis Metzler Clement: A Pioneer of the Central Pacific Railroad|url=http://cprr.org/Museum/Lewis_Metzler_Clement.html|publisher=Central Pacific Railroad Photographic History Museum}}</ref> the original (Track 1) summit grade remained in daily use from June 18, 1868, when the first CPRR passenger train ran through the Summit Tunnel, until 1993 when the [[Southern Pacific Railroad]] (SP) (which operated the CPRR-built [[Oakland]]-[[Ogden, Utah|Ogden]] line until its 1996 merger with the [[Union Pacific Railroad]] (UP)) abandoned the 6.7 mile (10.7&nbsp;km) section of Track #1 over the summit running between the Norden complex (Shed 26, MP 192.1) and the covered crossovers in Shed #47 (MP 198.8), one mile east of the old [[Flying junction|flyover]] at Eder. All traffic has since operated over the Track #2 grade crossing the summit {{convert|1|mi|km}} south of Donner Pass through the {{convert|10322|ft|m|adj=on}}-long [[Tunnel No. 41|Tunnel #41]] running under [[Mount Judah]] between Soda Springs and Eder. SP made this change because the railroad considered Track 2 and Tunnel 41 (which was opened in 1925 when the summit section of the grade was finally double tracked) to be easier and less expensive to maintain during the harsh Sierra winters than the Track 1 tunnels and [[snow shed]]s over the summit.<ref>{{cite web|author=Cooper, Bruce C.|url=http://cprr.org/Museum/Sierra_Grade_8-2003/Donner_Pass-Summit_Tunnel/index.html |title=Summit Tunnel & Donner Pass |publisher=CPRR.org |date=August 2003}}</ref>

In conjunction with major ongoing upgrades and expansions being made to the [[Port of Oakland]] in order to better accommodate the rapidly growing North American trade with Asia and the Pacific, the cooperation of UP, the Port's principal rail partner, has been sought to "construct a second track and raise tunnel clearances over Donner Pass for container trains linking California with the rest of the country."<ref>{{cite web |url=http://www.portofoakland.com/newsroom/pressrel/view.asp?id=26 |title=Newsroom |publisher=Port of Oakland |access-date=2010-05-14 |url-status=dead |archive-url=https://web.archive.org/web/20101126210226/http://portofoakland.com/newsroom/pressrel/view.asp?id=26 |archive-date=2010-11-26 }}</ref> This would likely require either a new parallel tunnel next to Tunnel 41 or the replacement of the summit section of Track 1 between the Norden complex and Shed 47; either would increase capacity and effectively eliminate delays currently caused by having to run all east and west bound traffic between Norden and Shed 47 over a single track. (To eliminate bottleneck delays the now single track {{convert|7.1|mi|km|adj=on}} section between Switch 9 (MP 171.9) at [[Emigrant Gap]] and Shed 10 (MP 179.0) west of Cisco would likely also have to be restored to double track.) Improvements were completed on the Sierra grade in November 2009, including increasing {{convert|18,000|feet|km}} of tunnel clearances in 15 restricted tunnels between [[Rocklin, California|Rocklin]] and [[Truckee, California|Truckee]] and upgrading {{convert|30|mile}} of signals to CTC, although the original Donner Pass grade (Track 1) was not restored. Since then trains of full-height or {{convert|20|ft|2|in|m}}, double-stack container cars have run over Donner Pass; some tunnels on Track 2 between Bowman and Colfax were not enlarged, so stack trains in both directions must use the older, tunnel-free Track 1 between those points.<ref>{{cite journal|url=http://www.railwayage.com/index.php/news/doublestacks-on-donner-pass.html|title=Doublestacks on Donner Pass|date=November 24, 2009|first=William C.|last=Vantuono|journal=Railway Age}}</ref>
{{multiple image|align=center|total_width=908
|image1=Donner Summit Panorama.jpg|width1=3748|height1=1470
|caption1=Panoramic view of Donner Summit from above CPRR Tunnel #6 with Donner Lake in the distance and [[Donner Peak]] to right
|image2=CPRR Grade at Donner Pass (USGS).jpg|width2=1000|height2=330
|caption2=Route of the original CPRR grade at Donner Pass
}}