COLFAX, Calif. — The American Society of Civil Engineers (ASCE) has recognized the Donner Summit Train Tunnel in California as a National Historic Civil Engineering Landmark. The Summit Tunnel is the longest of the 15 tunnels that were built for the Central Pacific Railroad as part of the Transcontinental Railroad and was the most difficult to build due to its location, altitude, and weather conditions workers faced.
A dedication ceremony on Saturday at the Colfax Heritage Museum honored the workers who built the tunnel in the 1860s and recognized the tunnel’s importance as the most difficult construction project at the western end of the Transcontinental Railroad.
“Throughout history, the Summit Tunnel has stood as a longstanding, significant pillar of local infrastructure and culture. While the project was the first to use high explosives in railroad construction, other aspects of the project added to its overall historic significance,” said ASCE President Feniosky Peña Mora, Sc.D., P.E., NAS, CCM, F.CIOB, NAC, Dist.M.ASCE. “As civil engineers, we take great pride in designing and constructing structures and sites that become legacies of our communities. The Summit Tunnel is a prime example of engineering innovation.”
Construction on the Summit tunnel started in October 1865 and it was completed in November of 1867. Workers hoped to have tunnel headings completed deep enough into both sides of the mountain before harsh winter conditions, which could bring up to 400 inches of snow over the course of a season, arrived at Donner Pass, however workers were unable to meet that goal, which paused construction for several months until the Spring of 1866.
Initially crews used black powder to break up the solid granite to clear the path. While black powder worked well for most blasting needs, the granite in Summit Tunnel is a hard rock that rendered black blast powder less effective. During construction of the Summit Tunnel, Alfred Nobel developed methods for manufacturing and handling nitroglycerine that made it a more powerful blasting agent in construction.
In February of 1867, crews started using nitroglycerine to blast through the rock. This was the first-ever use of nitroglycerine in the United States for railroad construction, and this new technique substantially increased the speed of construction. The Summit Tunnel also pioneered the use of nitroglycerine manufactured on-site in the United States. Despite the dangers of using nitroglycerine to build the tunnel, only one worker died during its construction.
The blasting to complete the tunnel was completed in August of 1867, and tracks were laid through Summit Tunnel allowing the first train to pass through on December 1, 1867. At the time of construction, Summit Tunnel was the highest railroad tunnel in the world at an altitude of approximately 7,030 feet.
In 1967, the tunnel’s floor was lowered by three and a half feet to allow taller trains to pass through. It remained in use until 1993, when all train traffic was routed to nearby Tunnel 41.
Plaques marking the Summit Tunnel as a National Historic Civil Engineering Landmark will be placed at the summit of Donner Pass.
ASCE represents more than 160,000 members of the civil engineering profession worldwide and is the oldest national engineering society in the United States. It recognizes historically significant civil engineering projects, structures, and sites worldwide. More than 350 projects worldwide have earned the prestigious title for creativity and innovation; almost all are executed under challenging conditions.
About the American Society of Civil Engineers
Founded in 1852, the American Society of Civil Engineers represents more than 160,000 civil engineers worldwide and is America's oldest national engineering society. ASCE works to raise awareness of the need to maintain and modernize the nation's infrastructure using sustainable and resilient practices, advocates for increasing and optimizing investment in infrastructure, and improve engineering knowledge and competency. For more information, visit www.asce.org or www.infrastructurereportcard.org and follow us on Twitter, @ASCETweets and @ASCEGovRel.