by Tunnel boring machines (TBMs) have existed since the mid-19th century, but their size and capabilities have expanded exponentially in recent decades. Driven by ambitious tunneling projects around the world, engineers have developed TBMs that can bore tunnels nearly 30 feet in diameter. Some of the largest machines now weigh over 13,000 tons and cost upwards of $500 million. They have enabled construction of tunnels deeper and longer than was previously possible.
The Bertha machine used for the Seattle Tunnel Project was one of the biggest ever built when it launched in 2013. However, it encountered problems and became stuck shortly after beginning its drive. After nearly 3 years of work, engineers were able to free it and complete the tunnel. While setbacks like this highlight the challenges of operating Global Tunnel Boring Machine underground, they have also spurred further innovation to make TBMs even more reliable and capable.
Boring the Gotthard Base Tunnel
One of the most impressive tunneling feats of all time was the construction of the Gotthard Base Tunnel through the Swiss Alps, completed in 2016. At 35 miles long, it is the longest rail tunnel in the world. Two giant TBMs named Cecile and Sela were used for the bulk of the boring. Each weighed over 13,000 tons and extended nearly 450 feet long when fully assembled.
Boring through the challenging mix of granite and gneiss rock formations in the Alps pushed engineering limits. Temperatures inside the tunnels reached over 140 degrees Fahrenheit. Maintaining the complex mechanical systems of the machines at such extremes was no small task. Yet the TBMs reliably excavated through nearly 15 miles of rock each over the course of 7 years to complete one of the most strategic transportation tunnels in Europe.
Mega Projects Driving Development
As populations and economies continue to grow rapidly in Asia and other regions, huge public works projects are seen as crucial for managing crowded urban areas and supporting commerce. Massive tunneling initiatives are a big part of the infrastructure development. China in particular has numerous ambitious plans that will require record-setting performances from tunnel boring machine.
The Beijing-Zhangjiakou High-Speed Railway aims to connect Beijing to co-host cities of the 2022 Winter Olympics Zhangjiakou with a new tunnel route through mountainous terrain. TBMs will excavate two main tunnels over 37 miles long, pushing the length records. India is also making major investments like the Mumbai Coastal Road Project involving complex underwater tunneling never before attempted in the country. As Global Tunnel Boring Machine solutions become more advanced, politicians view them as viable options for congested areas.
The Hong Kong-Zhuhai-Macau Bridge was completed in 2018 using TBMs to build longest underwater tunnels ever at over 16,000 feet long. The ambitious Suez Canal expansion project in Egypt included tunnel sections excavated by some of the largest machines to date. As global infrastructure needs escalate, tunnel boring technology will be crucial for executing bold mega construction endeavors.
Future of TBM Technology
Manufacturers are continuously integrating the latest technological capabilities into tunnel boring machines. Advanced sensor packages, robotics, artificial intelligence, and automated processes allow modern TBMs to operate with unprecedented precision, productivity, and safety. Cutting heads can be remotely controlled to gracefully navigate intricate geology. Machines can even partially assemble and disassemble themselves during assembly and transportation to job sites.
As environmental regulations tighten around construction emissions and impacts, ‘greener’ TBMs are a focus. Hybrid diesel-electric models and even fully electric variants are in development that would eliminate fossil fuel usage and emissions within tunnels. The possiblity of fully autonomous operation with no human workers required inside active machine environments is also being explored. Such advances foreshadow how tunnel boring technology will help enable a new generation of ambitious tunnels shaping 21st century infrastructure globally.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile itAdvanced sensor packages
