Science has come a really long way now and the once distant idea of gigantic robots and gargantuan machines roaming around on our planet finally seems to be getting closer, a great example of such ideas turning into reality is Big Bertha, the largest tunnel boring machine on the planet. As its name implies, Big Bertha is definitely big, in fact it is an absolute marvel of engineering with its 326 feet long body that weighs around 6,700 tons. This tunnel boring machine was designed and manufactured for Alaskan Way Viaduct replacement tunnel project launched in Seattle in order to provide a more effective transportation route over there.
Parts for Big Bertha were in Japan by Hitachi Zosen Sakai works and the machine was assembled in Seattle, the machine saw completion in the June of 2013 and began digging the 2 mile long tunnel in the 30th of July. The tunnel that Big Bertha was made to dig was a staggering 150 feet underground and would pass through many kinds of materials, including soft clay, hard rock and underground water bodies as well. This humungous boring machine has a drill head that has a 57 feet diameter and is made up of a variety of parts, all of which need to be replaced and maintained every now and then.
Big Bertha’s journey through the underground has been full of surprises and setbacks, right after digging had begun, Big Bertha’s main bearing seal system got damaged in December 2013, leading to a halt in operations that would last for 2 years. After finally digging an access tunnel to repair the damage, Big Bertha began digging once again in 2015, but disaster struck again in early 2016 when the digging process lead to a sinkhole forming near the area of operations. Hiccups such as these lead to a two year project taking 4 years to complete.
However, Big Bertha has finally finished boring the tunnel and the project is set to be completed somewhere between 2018 and 2019. Big Bertha’s primary job was to carry out the digging process bit by bit, but the machine was also equipped to stabilize the tunnel as it cut its way through the earth. As the machine pushed its way through tons of dirt, it was also equipped to build the tunnel rings that would support the completed tunnel, this ensured that the tunnel would not collapse behind Big Bertha.
One of the most demanding things about this giant of a machine was to maintain its drill head, workers would have to inspect and replace every part of the drill head quite frequently, the drill head was designed with various gaps to make accessing the parts easier, but the endless amount of dirt and water getting in the way made things a lot more harder to manage. The Big Bertha tunnel boring machine caused a lot of trouble and was quite demanding, but it managed to get the job done.