Tunnel Business Magazine

JUN 2018

TBM: Tunnel Business Magazine is the market leader for North America. TBM is written for leading professionals in all aspects of tunneling and covers project stories, design elements, contracting strategies, legal issues, new technology and more.

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function or failure, in order to preserve the existing nature around underground constructions. For this edition, Han Admiraal and An- tonia Cornaro, co-chairs of ITACUS, pre- sented their new book "Underground Un- veiled: Planning and Creating the Cities of the Future." The book explores a new way of thinking about underground spaces, in- tegrating visions of all stakeholders: urban planners, urban designers, architects, ge- ologists and engineers. The authors give a global overview of innovative concepts ongoing around the world, supporting the idea of under- ground space as a lever of sustainable development, including underground farms, multi-functional tunnels and un- derground pedestrian lines. Contractual Practices in the 21st Century Underground construction is a fast- growing market sector and a special one in many regards. The underground works differ from high-rise construction because the creation of the necessary space within the ground and the nature of the ground is often unpredictable. Underground con- struction therefore involves greater un- certainty and greater risk. The risk of differing ground conditions is at the roots of many issues in contract- ing processes. When the ground within which a tunnel is to be built is worse than expected, the tunnel is more expensive and takes longer to build than anticipated. ys, fixed-price, fixed-time con- tracts, as they are often successfully used in high-rise, have not proven to be effec- tive in underground works, causing high- er costs and time overrun. FIDIC (The International Federation of Consulting Engineers) and ITA, both organizations recognized by the United tions, the World Bank, Development Banks and the International Tunnel Insur- ers Group (ITIG), have formed a joint Task Group (TG 10) to propose a new form of contract for underground works: The Em- erald Book. Approached during roundtables of the Open Session, the major points included in the Emerald Book are: • Balanced sharing of the ground re- lated risks between owners (ground conditions risks) and contractors (time and cost risks in the expected ground conditions) • Provisions for dealing with unfore- seeable ground conditions will be included in the general conditions of the contract • A provision for a standing Dispute Avoidance and Adjudication Board (DAAB) • Guidance for the preparation of ten- der documents Innovative Initiative to Face Wastewater Treatment Issues in the Middle East Abu Dhabi Sewerage Services Com- pany (ADSSC) has developed the Strategic Tunnel Enhancement Program (STEP), a huge gravity-driven hydraulic wastewa- ter tunnel network solution to relieve the hydraulic burden on the existing sewer- age network and to accommodate the de- mand created by the projected population growth in the Emirate of Abu Dhabi. The deep gravity sewerage system's aim is to collect wastewater in Abu Dhabi Island and the mainland. The program in- cludes one of the deepest gravity sewer tunnels in the world, and the first and largest in the Gulf Region. The 41-km long deep sewer tunnel was completed using a total of eight earth pressure balance (EPB) tunnel boring ma- tilizing a pre-cast concrete bolted segmental structural lining along its entire length. The tunnel varied in depth from 30 to 85 m deep and the 17 shafts along the tun- nel route (at approximately 2.5 km centers) were all constructed using diaphragm walls for temporary ground support. The finished internal diameter of the tunnel varied from 4 to 5.5 m, which included a corrosion protection lining comprising an HDPE primary lining and unreinforced concrete secondary lining to protect the tunnel from acid attack and corrosive compounds typically found in sanitary waste water environments. In addition to the 41 km long tunnel, STEP includes 45 km of "link sewers" to connect the existing sewerage system to the new deep tunnel, and one large pump- ing station which will accommodate an average wastewater flow of 1.7 million m3/day by 2030. Looking Ahead The whole congress showcased the best of the tunneling industry, and the upcom- ing evolutions of underground construc- tion seem to lie in digital applications and innovative concepts of underground spac e completely autonomous? How can innovative sys- tems already working for aeronautics, rail and automotive industries be applied to the tunneling? All these questions under- lined the congress and shall be addressed in a short-term future. The Robbins Company was among the U.S. companies present in the exhibit hall. Technical discussions and panels are a hallmark of the World Tunnel Congress. Focused Working Groups meet at WTC to discuss and share information on best practices. F E A T U R E S T O RY 3 4 TUNNELINGONLINE.COM TBM: TUNNEL BUSINESS MAGAZINE // JUNE 2018 Global Tunneling Activity • Global output (2016): €86 billion ($103 billion US) • The yearly average of constructed tunnels: 5,200 km (3,200 miles) • The average growth of around 7% per year is twice the global construction growth

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