Tunneling through the Sierra inch by inch
October 3, 2005
By Gordon RichardsThe Sierra Nevada at Donner Pass was both a feared and exhilarating mountain crossing until the Central Pacific Railroad finally conquered it in 1868.The construction of the summit tunnels has been compared to a war by many writers and visitors over the years. History remembers well the battle that the mostly Chinese laborers waged to drill and blast their way through the mostly solid granite.More credit for the Donner Pass route should really be given to Dr. Daniel Strong of Dutch Flat. It was Strong who invited and guided Theodore Judah to the area in 1860, when Judah was searching for a rail-feasible pass over the mountains. The shallow canyon above the south side of Donner Lake was originally named Strong’s Canyon, but today is known as Lakeview Canyon. Strong went on to be a Central Pacific Board of Directors member.By 1862, Judah laid out the exact route of the summit tunnels and the traverse along Schallenberger Ridge, then known as Donner’s Backbone, but other engineers, such as Samuel Montague and Lewis Clement, completed the final survey locations and construction staking for the Chinese labor crews.In the stretch from Cisco to Schallenberger Ridge, crews had to dig more than 5,150 linear feet in nine tunnels to maintain the grades engineered by Judah. Almost all of these tunnels were in granite that was stronger than steel. The 1,659-foot-long Summit Tunnel, No. 6, required the longest time, more sweat and more explosives than all of the other tunnels combined.
The struggle within the mountainCrews started Tunnel 6 in the fall of 1865 as the railhead was still down the mountain below Cisco, but the crews were driven out of the Sierra by early heavy snow without making much of a dent at the portals. As early as possible, after the snow melted, the heavy work began in the summer of 1866. The two portals were started with the Chinese crews starting in the top of the 16-foot-high bore.The 11-foot-wide shelf was worked at a man’s height, and subsequent crews drilled and blasted the shelves out down to rail grade. Work went on around the clock during the summer of 1866 and through the winter into 1867. As that was going on, the other tunnels were also being pushed through with as many men as possible at each rock face.Hard labor made easierThe normal method was to use hand sledgehammers to drive iron hand drills into the unforgiving rock. When the hole was finally deep enough, usually 8 to 12 inches, companion holes were also drilled. Once a face was full of holes, the black powder was loaded in, the fuses carefully lit, and the powder monkeys ran for cover. The explosion was deafening and the tunnel filled with smoke. After the smoke cleared, the rubble would be carted out by wheelbarrows and dumped over the side of the cliffs.Most Central Pacific tunnels were blasted using this method. The progress was painstakingly slow, averaging 1.5 feet to 2.5 feet per 24 hour shift. So construction manager Charles Crocker and Superintendent James Strobridge approved the use of nitroglycerin in February 1867. After a shipment of the liquid form blew up in San Francisco in April of 1867, killing several men, the inert ingredients were mixed in a shed near the top of the pass to create the powerful explosive. Chemist James Howden mixed up the rock shattering sticks of the early form of dynamite, which then sped up the tunnel headings progress by up to 4 feet a day. Only tunnels 6 and a portion of 8, east of the pass were shot and blasted with nitro-glycerin. Still this was not fast enough for the impatient Central Pacific Railroad executives.
The middle portals are openedIn August of 1866, Crocker decided to open a 75-foot-deep vertical shaft over the middle of the Summit Tunnel shaft. A hand winch was first set up to haul the rock up the shaft. It was quickly traded for a small steam engine, that was housed in a snow resistant building that hauled bucket loads of rock up the shaft. Once the shaft reached the elevation of the rail line, two new headings were started east and west to speed the tunnel forward twice as fast.With four headings and nitroglycerin, full shifts of Chinese laborers, and a continuos stream of supplies coming up from Sacramento, progress moved forward. The goal was to complete the tunnel and track by the fall of 1867. Track had already been laid from Truckee to the Nevada state line, and it was hoped that the gap would be completed before winter set in again.Storms of fury descendJudah had estimated that it would not take more than a few snow plows to keep the railroad open through the winter. The winter of 186566 showed that it would take more than that, but would still not be a major obstacle to construction and service. Work stopped on all fronts that winter, and as spring thawed the deep banks and drifts, crews wielded shovels to clear the wagon road and rail grade.By the fall of 1866, the rail head reached Cisco and work was planned to continue all winter. Forty-four storms that lasted from a few hours to two week long gales thrashed the Sierra that winter. As much as 10 feet of snow fell in 13 days in March. Winds piled up fantastic drifts that crushed the buildings that were erected to protect the tunnel workers. The only safe place from snow was in the tunnels, where the danger remained the nitro and falling rock.
As winter progressed, the snow tunnels at the portals were extended up to as long as 500 feet further. Rock was continuously wheeled out and dumped into piles of rock and ice. Snow slides crashed down on both Chinese and American workers in cabins that were strung out along the route, with as many as 20 being swept away by a slide near Tunnel 9 above Donner Lake.The summit finally crossedThe Summit Tunnel was finally holed through and completed after a year and a half of constant toil and sweat. In November of 1867, the rock work was done and the track laying was begun. All of the other tunnels were done and track was laid back up the mountain from Truckee into Coldstream Canyon by then. Through the near precision engineering of tunnel engineer Lewis Clement, all four headings of Tunnel 6 came to within 2 inches of the planned alignment.The railroad crews rushed the track laying through the tunnels, into Strong’s Canyon and along Donner’s Backbone toward the east. Despite their best effort the Storm King began to dump heavy snow on the Sierra and track work was stopped before the end of December. Another winter would delay forward progress of the railroad through Nevada. The gap in the rails would be bridged by stages and freight wagons traveling over the snow on sleighs from the summit to Truckee.In April of 1868, the crews returned to the mountain and began to chip and shovel up to 30 feet of ice and snow on the grade and tracks on the Summit. By June 14 the grade was dry and ready and in three days, seven miles of track were laid from the Summit down to Strong’s Canyon. It wasn’t until June 17 that the gap was finally completed. A spike driving ceremony was held and the Sierra was conquered.Gordon Richards is the president and research historian for the Truckee Donner Historical Society. Comments and history information are always welcome. Please visit the Truckee Donner Historical Society Web site at http://truckeehistory.tripod.com. The e-mail address is firstname.lastname@example.org. You may leave a message at 582-0893. Past articles by Gordon Richards are available at sierrasun.com in the archives.