In the early stages of the Seattle tunnel project, the massive tunnel-boring machine named Bertha encountered significant challenges, particularly when it hit an obstruction shortly after commencing work. Initially, on December 6, 2013, Bertha was halted about 1,000 feet into the 1.7-mile tunnel due to what was believed to be a large boulder or potentially a buried rail car from earlier construction periods. This incident raised concerns about the project’s timeline and costs, which were already under scrutiny due to previous delays and technical issues.
After extensive investigation and repair efforts, it was determined that Bertha had struck a steel pipe left underground from a prior project. This discovery led to a massive repair operation that delayed tunneling for nearly two years. The machine’s cutter head was eventually brought to the surface for repairs in March 2015, revealing more extensive damage than initially anticipated. Following these repairs, tunneling resumed in December 2015.
Bertha continued its journey under downtown Seattle, overcoming various obstacles until it finally broke through to the northern portal on April 4, 2017. The entire tunnel boring process took longer than expected, with the completion of the tunnel delayed until early 2019. The new State Route 99 tunnel officially opened to traffic on February 4, 2019, marking the end of a tumultuous project that had started with high hopes but faced numerous setbacks along the way.
The completion of this $1.4 billion project replaced the aging Alaskan Way Viaduct and created a vital transportation route for Seattle, despite the challenges faced during its construction. The project not only succeeded in providing a new highway route but also set a precedent for future large-scale tunneling projects worldwide.
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[1] https://www.historylink.org/file/10685
[2] https://en.wikipedia.org/wiki/Alaskan_Way_Viaduct
[3] https://www.seattletimes.com/seattle-news/transportation/bertha-tunnel-boring-machine-history-viaduct-replacement/
[4] https://en.wikipedia.org/wiki/Bertha_(tunnel_boring_machine)
[5] https://tunnelingonline.com/retracing-bertha-journey/
[6] https://seattlebusinessmag.com/manufacturing/spin-zone-bertha-maker-hitachi-zosen-bites-back/
[7] https://en.wikipedia.org/wiki/State_Route_99_tunnel