Technical delivery at RETC 27 Jun 2013
Shani Wallis and Judy Green, TunnelTalk
Washington DC provided the perfect backdrop to a session of the RETC that explored progress on many of the capital infrastructure projects across the United States and delivered the results of technical studies and investigations into various excavation methods and processes. Design and progress of major overseas projects added to the technical discussions, and a busy exhibition hall presented further opportunity to appreciate industry advancements.
The consensus of opinion among more than 1,350 delegates at the 2013 session of the Rapid Excavation and Tunneling Conference (RETC) in Washington DC was that Conference presentations were of high technical quality and interest. Experiences gathered during the advance of different tunneling projects provided new understandings and appreciations of different excavation processes and associated techniques and systems.
EPBM operation, as the selected method of excavation on many of the tunneling projects in North America currently, was heavily represented with several papers describing specific aspects of the method. One paper described how the use of soil conditioning foams can cause the creation of a bubble of compressed air at the top of an EPBM excavation chamber and lead to a variety of problems including a drop in EPB pressures between strokes, and the possibility of blowouts through the screw or to the surface. Key parameters for detecting such air bubbles in the plenum and methods of releasing the pressure were presented.

Engaging sessions and a comprehensive exhibition made for a successful RETC

Another paper described how current occupational health and safety regulations governing man-entry interventions into the excavation chambers of soft ground TBM systems under hyperbaric conditions have not kept up with technological advances and now require review and revision. Two further papers in the same session focused on the use of soil conditioning agents, describing an experimental study of such agents on soil abrasion and cutter wear, and offering to untangle the mystery of soil conditioning in EPB tunneling.
Obituary: Andy Peterka
Sadly, it was learned at the RETC that Andy Peterka died on March 24, 2013 at his home in Fort Worth, Texas. Andy, aged 75, had a long career and was well known by so many in the US tunneling community. He started as a designer/draftsman working for John Taber at Memco in Wisconsin. Memco cutter wheel machines bored the San Francisco BART metro tunnels and Memco digger shields excavated the Castaic tunnel as part of the California State Water project. Martin Herrenknecht had his introduction to TBM technology on Memco machines. Andy later started his own TBM company, Zokor. From the late 1960s to the early 1980s, Andy was a jet-setter, selling his machines all over the world. Andy's last sale was for the Tehran metro on the eve of the overthrow of the Shah and the subsequent revolution in Iran; Zokor machines excavated many of the Tehran metro tunnels. Andy later worked for Joe Sehulster, producing precast concrete liner segments for numerous projects including the San Antonio Flood Relief Tunnels. He later started producing segments himself for Economy Precast in association with Elmore, Kenny, Gifford-Hill (Hansen) and Affholder for various projects including the North Metro Interceptor Sewer for the City of San Diego; the Benbrook project for the Tarrant Regional Water District, Texas; the Hollywood Bypass Tunnel for the Department of Water and Power; the Lower Sacramento River Crossings for the Sacramento Regional Sewer District; and the New Mississippi Outfall Project for T-Rex in Denver. He worked closely with Ronald Raymond of Construction Polymers in providing innovations in segment design from Europe in first time applications in the USA. Some of his visions are still circulating in the industry and perhaps may be used in the future. The tunneling industry is proud to have had Andy as part of its family.
The last presentation of the session was given permission by the session chair to overrun by more than half an hour into the lunch break as delegates stayed on to hear the story of various challenges overcome by the team working on the Queens bored tunnels for the East Side Access rail tunneling project in New York City.
The design of segmental linings was another topic that was well represented. One presentation described the development of a concrete segment system that has no Portland cement or steel reinforcement. Instead, the process uses synthetic fiber reinforcement and geopolymer binder to produce segments that take substantially fewer carbon emissions to manufacture, while at the same time benefiting from increased durability. The segmental lining of the Brisbane Airport Link bored tunnels in Australia was presented as having the largest steel fiber reinforced concrete segments in the world. Design of the segmental linings for the Waterview highway tunnel in Auckland, New Zealand, and for the largest TBM bored tunnel in the world at the moment, the Alaskan Way replacement tunnel in Seattle, were described in detail.
A busy time for the delegates at the Conference started with a set of workshops and special sessions on Sunday, ahead of the program of four simultaneous sessions on Monday, Tuesday and Wednesday morning. Of these TunnelTalk attended the workshop on Risk, Uncertainty and Hard Decisions. A set of exercises demonstrated how easily communications can become misinterpreted and confused, and how assumptions can be completely wrong. A series of panel discussions with representatives from the owner, contractor, and designer sides, then explored further the relationship between each, and the various areas where communications can break down or require substantial effort to remain open and productive.
Much of the success of projects was attributed to the experience of workers in the construction team. It was acknowledged that passing responsibility down the chain of command for newer members of the team to gain experience was important for the future of the industry.
The social events of the Conference included the second meeting of the Women in Tunneling group. Attended by about 45 women working for contractors, clients, consultants and suppliers, and including members of the press and wives and partners of professionals in the industry, the aim of the group is to provide a forum for networking among women in the tunneling business who may, on occasion, find themselves isolated or particularly alone among a predominantly male team. A chance to get together and share experiences was appreciated by those who attended. There remains potential to increase the number of attendees at the next meeting planned for NAT in Los Angeles in June next year.
An exhibition of more than 180 booths made for a comprehensive representation of industry suppliers and service providers.
The event was well organized by the team at SME, and the Marriott Wardman Hotel presented a very comfortable venue for the technical sessions, the exhibition, and the major social events. The lack of internet wifi in the conference and exhibition areas was a service that was missing, however, and microphones in the halls for those with questions from the floor would have been useful to enable the audience to hear. But all in all, a highly productive, instructive and enjoyable conference.
Coming tunneling conferences organized by SME
Cutting Edge 2013:
Mega Projects

3-5 Nov, 2013
The Westin Seattle Hotel
1900 Fifth Avenue
Seattle, Washington
NAT 2014
Tunnelling: Mission Possible

22-25 June, 2014
J W Marriott
Los Angeles, California
2015 RETC
7-10 June, 2015
New Orleans, Louisiana
NAT with WTC 2016
7-10 June, 2016
Marriott Marquis
San Francisco, California
Copies of the printed and DVD volumes of the proceedings are available from the SME.
References
RETC forum on risk and uncertainty - TunnelTalk, May 2013
RETC 2013 exhibition preview - TunnelTalk, May 2013

           

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