Tunnels were initially constructed around 3,000 years ago mainly for defensive purposes. The invention of dynamite in 1867 by inventor Albert Nobel blasted the construction of tunnels forward. Since then, tunneling technology has advanced significantly, with interesting projects starting up all the time.
A Quick History of Tunnels
Babylonia and Persia were the first to build tunnels to transport goods. They transported the most important resource in that desert environment – water. The irrigation tunnels enabled life to flourish in an otherwise hostile environment and some of them are still operational to this day.
The Greeks and Romans took, and perfected tunnel making to transport water, drain marches, and enable underground pedestrian traffic. Around 36 BC, a 4,800-foot-long and 30-foot-high pedestrian tunnel was constructed between Naples and Pozzuoli – complete with ventilation shafts.
The middle ages saw the advent of, first, the canal and, then, the railroad tunnel. The invention of the railroad initiated a boom in tunnel construction as railroads spread all over the world. The first model of the Tunnel Boring Machine as we know it today was created by James S. Robbing in 1952.
Gotthard Base Tunnel
The world waited a long time for the longest and deepest railway tunnel – 17 years to be exact. The Gotthard Base Tunnel constructed in Switzerland was opened in June of 2016. It sits 7,500 feet below the top of the Alps above it. It’s 35 miles long and connecting Zurich and Milan – beating the Seikan Tunnel in Japan built in 1988.
Engineers battled 28 million tons of 73 different types of rock to deliver a project that was both on time and budget – a feat in and of itself. Constructed using a Tunnel Boring Machine 410 meters long, the Gotthard Base Tunnel reduces travel time for freight and passengers while eliminating the environmental impact on sensitive alpine environments.
Alaskan Way Viaduct Tunnel
In July of 2013, construction started on the Alaskan Way Viaduct Tunnel to replace an existing elevated freeway. After the Nisqually earthquake in 2001 damaged the existing freeway, experts estimated that there was a 1 in 20 chance of the freeway being damaged again in the next decade. That information inspired municipalities in and around Seattle to develop a replacement project.
After many years, they settled on a double-decker highway tunnel constructed using a Tunnel Boring Machine – called “Bertha”. Bertha was, at the time, the largest Tunnel Boring Machine in the world. The final cost of the project was 3.1 billion U.S. dollars. It finally opened to traffic in February of 2019.
The project took 6 years from the start to completion largely due to a 2-year delay starting just 6 months after tunnel boring started. Bertha overheated and shut down. A 120 ft shaft was created to allow the repairmen to reach the cutting head. Construction of this repair shaft accounted for most of the 2-year delay.
Parities are still litigating over who is responsible for the $642 million repair bill of the Tunnel Boring Machine. Most interestingly, evidence, including parts of a steel well casing that TBM hit prior to overheating and journal entries by the project manager, has gone missing during litigation.