This article was taken from the June 2015 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
The journey into Seattle's new tunnel ends abruptly after 311 metres. The world's biggest tunnel boring drill -- Bertha -- could not get any further. It is a colossus of 6,350 tonnes, more than 100 metres in length and 17.5 metres in diameter. Its task: to carve out a 3.2km-long tunnel to replace the Alaskan Way Viaduct, an old city highway that was damaged in a 2001 earthquake. If the salvage mission works, the first cars might be passing through the tunnel by 2017.
The glitches in Bertha's journey are at the centre of local controversy. In December 2013, the machine overheated, leaving the $3.1 billion (£2 billion) plan to replace the viaduct unfinished, and Bertha stranded without a reverse gear (you can just make out the back of Bertha way down the tunnel here). The damage to the drill has been attributed to broken seals across the front of the drill head. "Currently, the machine is in the process of being repaired," says Laura Newborn from the Washington Department of Transportation.
On March 3, engineers were able to reach the SR 99 tunnelling machine via a specially constructed 37-metre-deep pit, and lift it into the daylight for repairs. "They will lift the front shield out in three pieces, then lift the entire cutter head to the surface," says Newborn. Whether it turns out to be that simple or not, Bertha can tell the world itself. Its Twitter account, @BerthaDigsSR99, has over 15,000 followers eagerly awaiting news from underground.
This article was originally published by WIRED UK
