An increased focus on infrastructure development in the United States and around the world has helped create a vibrant tunneling and underground construction industry with a number of mega projects underway and more being planned in cities around the globe. A reflection of the overall good health of the industry could be found in Boston, MA, June 11-14 at the 2023 Rapid Excavation & Tunneling Conference (RETC). More than 1,400 people registered for the three-day conference that featured industry-leading technical sessions, short courses, networking events and a packed exhibit hall. The latest technologies for tunneling and underground construction were discussed in technical sessions and on display in the exhibit hall.
“The 2023 RETC conference in Boston gave us a snapshot of the current state of the tunneling industry,” Shemek Oginski, project manager, JF Shea Co. Inc. told T&UC. Oginski served as the conference chair for the 2023 edition of RETC. “The variety of the projects currently under construction is larger than ever before. New technologies and advancements in tunnel boring machines (TBMs) are pushing the boundaries beyond what was considered possible just a few years ago.”
During the conference, information and lessons learned about the latest technologies and from the largest and most cutting-edge projects were discussed in the technical sessions. There were a number of presentations focused on the subject of TBM technologies and advancements including lessons learned from projects such as the Brenner Basis Tunnel, the Ashbridges Bay Outfall Tunnel below Lake Ontario and a new water supply in Oslo, Norway, just to name a few.
The technical sessions were by no means limited to discussions about TBMs. Of the 133 sessions, topics included: Design-build projects; Difficult ground; Geotechnical considerations; Design; Ground control approaches and methods; Microtunneling and trenchless technology; Shafts caverns and mining; Ground support and final lining; International projects; Tunnel rehabilitation; New and innovative technologies; Future projects; Contract practices; Health and safety and sustainability; Risk management and Project planning.
When preparing the programming for the RETC, Oginski and the rest of the program committee considered the trends of the industry and worked to create a program that was both timely and informative.
“Many mega projects are either in progress or at the design and procurement stage, while many more are awaiting funding and further development. Projects that were on the waiting list for a long time are now being funded and have realistic schedules for delivery,” Oginski said. “In the New York area, the Gateway project and Second Avenue Subway are prime examples of this while on the West Coast, the Silicon Valley BART/VTA extension in San Jose will be the first single-tube metro project in the United States.
“Concurrently, tunnel project delivery methods are changing as well. The typical design-bid-build project delivery has continued to be used mostly for smaller projects or projects with well-defined geological conditions and other constraints. Conversely, mega projects in dense urban areas are being delivered via traditional design-build models, and increasingly through innovative progressive design-build and Construction Management At-Risk (CMAR) methods, where the potential contractors are prequalified based on their experience, capabilities, project understanding, safety records, design credentials and financial standings,” Oginski said. “Owners typically prequalify two or three contractors or joint ventures based on various scoring systems where the cost proposal is only one of many factors influencing their decision. Wide adoption of these new delivery methods is changing the way contracts are awarded and how contractors must adopt and procure the work.”
While many presentations are on lessons learned and about the successful completion of projects, others are designed to face challenges head on.
“The RETC conference discussed many big challenges facing the tunnel industry,” said Oginski. “Many underground projects are becoming more complex and more demanding on designers, contractors and owners. Intense technical knowledge and vast experience is now required from the professional in this field. The projects require people from various fields, not only with strict technical and engineering background but financial, legal, risk management, medical, safety, public relations and knowledge of various outside organizations, both public and private, that may impact the way a project is delivered, designed or constructed. This year’s RETC conference brought together owners, contractors, designers, suppliers and consultants who could meet and exchange ideas that are typically not discussed in another setting.”
In addition to the technical sessions, RETC included an exhibit hall with 183 vendors in 209 booths showcasing the latest and greatest technologies. There were also a number of networking functions such as the Owners Forum, Women in Tunneling breakfast, UCA scholarship and mentor program and the Teach the Professors program.
The welcome luncheon included a presentation that focused on the lessons the Massachusetts Water Resources Authority (MWRA) has learned from decades of tunneling projects in the greater Boston area. Fred Laskey, executive director of MWRA, credited the area’s tunnels with creating some of the best and cleanest water and urban beaches in the United States. The water and the pristine conditions currently found in Boston were not always so clean, according to Laskey, who said the city was “built with its back to the harbor because of the pollution that once existed.”
Commitment to infrastructure projects including more than 100 miles of water tunnels helped change that. Now, the MWRA serves 3.1 million people and provides an average of 200 million gallons of clean water to residents per day.
Winston Churchill said in a 1948 speech, “Those who fail to learn from history are doomed to repeat it.” Kathy Murtagh, director of tunnel redundancy at MWRA, spoke about the lessons the MWRA has learned from its decades of building tunnels so that mistakes of the past will not be repeated in projects of the future that are part of ongoing designs of its next deep-rock tunneling project, the Metropolitan Water Tunnel Program (MWTP). Focusing on a handful of tunnels including City Tunnel, Malden, Dorchester Tunnel, Inter Island Tunnel and Braintree West, Murtagh gave a presentation that was part history lesson and part planning for the future.
Because of past projects, the MWRA has learned how to tunnel through various ground conditions and fault lines. The MWTP will be built in the same conditions and cross the same fault lines. Among the lessons, Murtagh noted that a lining failure on the Dorchester tunnel that took six years to fix has had a heavy influence on future work, as did a fire at the Inter Island project.
Among the lessons learned are:
Superiority of tunneling versus cut and cover.
Optimize tunnel heading lengths to balance multiple considerations and risks.
Investigate faults early.
Tunneling in the Argillite can be very variable.
Don’t expect to speed.
Plan for water.
Select shaft sites carefully.
Maintain good relationships with host communities/neighborhoods.
Previous experience serves as an important risk-mitigation tool.
In additon to programing focused on technical challenges, RETC included sessions and networking opportunities to address the workforce issue in the industry.
“Given the ever-changing and more demanding tunneling industry, the workforce is having a hard time keeping up,” Oginski said. “There is a vast shortage of skilled people on almost every level, from managers, engineers, experienced supervision and quality-control staff to tunnel workers, laborers, equipment operators and safety professionals.
“The RETC conference promotes the industry on many different levels and encourages the next generation of students to choose work and study relating to the underground profession,” he said. “The RETC Committee awarded 12 conference scholarships this year for students interested in attending the tunneling conference. The committee also awarded six executive scholarships with financial assistance for students pursuing degrees related to underground construction. Furthermore, attending the conference gives participants of any level a sense of community that helps build personal relationships, advance collective knowledge and promote pride in being a part of this industry.”
The UCA will host the North American Tunneling (NAT) Conference in Nashville, TN June 23-26, 2024 and RETC will be held again in Dallas, TX in 2025. n