Whilst there is a multitude of reasons for tunnel conveyor belt installation, one of the biggest is as part of vast tunnel boring machines to efficiently remove spoil, muck and debris from excavation sites.
Since the development of the modern TBM, a bespoke machine that safely and efficiently drills tunnels, clears away debris and lines the sides smoothing, allowing for a safe and optimally shaped tunnel wall perfectly suited for large-scale tunnel projects.
From 1988 until 2016, the longest railway tunnel was the Seikan Tunnel in Japan, which is part of the Hokkaido Shinkansen, a 149km high-speed rail line, 23km of which is spent under the sea bed of the Tsugaru Strait separating the island of Hokkaido from Honshu, the main island of Japan.
The tunnel itself is 53.8km in length, three kilometres longer than the Channel Tunnel, although the Channel Tunnel has the longest underwater rail tunnel section, a core complication of the tunnel when it was originally designed and created.
Both of these tunnels would eventually be beaten by the longest railway tunnel ever made, the 17-year endeavour to build a tunnel underneath the Alps.
The Gotthard Base Tunnel spans over 57km and is such a long tunnel that the weather on both sides of it can be completely different, with a temperature difference that can reach as high as ten degrees Celsius.
Interestingly, whilst the GBT is the largest railway tunnel in the world, the largest transport tunnel of any kind is the full length of Line 3 of the Guanzhou Metro in China, which spans 800m more than the GBT, not including its branch line between Tianhe Coach Terminal and Tiyu Xilu.
It needs to be this long because it is one of the busiest and most congested rapid transit systems in the world, and in certain places operates officially over 100 per cent capacity, with two extra lines (Line 18 and Line 26) aiming to relieve this congestion.