| NEWS
Stockholm grid bore finish SWEDEN - The tunnel drive for Stockholm’s new power cable tunnel was recently completed. The client is Svenska Kraftnät (Sweden’s
National Grid company) and is being undertaken to strengthen the electricity supply network within the capital. Svenska Kraftnät’s 13.5km-long power
cable tunnel project is located between Anneberg and Skanstull, in Stockholm. The contractor is Hochtief-Implenia JV,
which used TBM ‘Elektra’, for the hard rock boring beneath the city. The Herrenknecht open gripper machine bored through rock 50m-100m below the surface, creating a 5m-diameter tunnel, and completing the drive in May. Although hard rock the tunnelling work
on the project required large volumes of injected grout. The tunnel passed under densely populated areas of Stockholm, several historic and sensitive buildings such as the University of Stockholm, museums and galleries, and its route also goes near Strömmen passage (part of the Baltic Sea). The tunnel connects power grid
substations located at Anneberg and Skanstull. The contract also includes six ventilation shafts, elevator systems, the construction of technical buildings for electrical equipment at Anneberg and the shafts across the city. The project is the second of four phases
in Svenska Kraftnät’s City Link project to boost the power grid.
Tata breakthrough at Chennai INDIA - The further tunnel breakthrough has been achieved on Phase II of the Chennai Metro Rail project. TBM ‘Kalvarayan’, from Herrenknecht,
completed the 867m-long drive from Ayanavaram station to arrive in the south shaft of Perambur station. It was the seventh TBM breakthrough by Tata Projects on Lot TU-01 of Phase 2 of the metro works. Tunnelling was complex between
Ayanavaram and Perambur with the alignment taking the TBM under railway tracks and platforms, densely populated areas, and navigating bored wells. Tata Projects is constructing the first
underground section of Corridor 3 of Phase 2. This 9km-long section is between Madhavaram Milk Colony and Kellys. The tunnelling works are using seven TBMs. The previous breakthrough was achieved in August 2024, when a Terratec TBM, ‘Kolli’, completed the 903m-long drive from Ayanavaram to Otteri station.
The 45km-long Chennai Metro Rail
Phase I opened in 2019, and a 9km-long, nine-station extension was commissioned in 2022. Phase 2 is a 118.9km network with 128
stations. It comprises three corridors: Corridor 3 from Madhavaram to Sipcot (45.8km); Corridor 4 From Lighthouse to Poonamalle Bypass (26.1km); and, Corridor 5 from Madhavaram to Sholinganallur (47km). It is due to be completed by the end of 2028.
China water tunnel TBM set CHINA - China Railway Engineering Co has unveiled its 10.23m-diameter single-shield TBM to part of the Xianglushan water diversion project. The TBM, ‘Fuhe’, is to be deployed No.6
auxiliary tunnel of the Xianglushan project’s Dali Section I, in the central part of Yunnan Province, in south-west China. The machine is to excavate a total length of 15.51km. Tunnel alignment is through complex
geology, comprising soft rock and high- pressure, water-rich sections. With a total length of approximately
190m, the TBM consists of a main machine, a service bridge, and 10 trailing support units, said the manufacturer. The entire system weighs 2,500 tonnes. It includes digital drilling rig and an anchor cable drilling system for face and vault support, working with integrated geological forecasting. There will be relatively steep gradients. The water diversion project is one of the
172 major water-saving and supply projects designated in China. This project aims to improve water supply in central Yunnan and its network extends over a total distance of 664km, with over 92% of the conduits consisting of tunnels. Once completed, it is expected to divert flows to support cities such as Kunming and Yuxi.
Last link for Delware US - A new procurement process is planned for the final connection of a new bypass tunnel to run under the Hudson River, in New York, as the last step on its US$2bn programme to fix leaks in the Delaware Aqueduct. The New York City (NYC) Department of
Environmental Protection (DEP) recently announced it would begin the new procurement and contracting process. In 2010, NYC announced a plan to repair
the leaking sections of the 136km-long Delaware Aqueduct, the longest tunnel in the world. by connecting a 4km-long
bypass tunnel around leaks discovered in the 1990s deep under the Orange County Town of Newburgh, adjacent to the Hudson. The project was paused in late 2024
November following the historic autumn drought, ending the existing construction contract and forcing the final connection to be completed under a new procurement process. Those challenges, plus plans to upgrade pumps, mean the final connection is not due for completion until after 2027. The final bypass connection requires an
eight-month shutdown and draining of the aqueduct, starting in October of any given year as demand is lower in winter.
Auckland outfall dig start NEW ZEALAND - Small diameter tunnel boring for a new wastewater pipeline in Auckland has started to improve water quality in the Manukau Harbour. The 1.2m-diameter TBM will help build
the new outfall to be located at Clarks Beach. It will install a steel pipeline and reach a receiving pit 10m-15m under the sea, from where the shield will be lifted out by a team of divers who will unbolt it from the pipeline and carrier pipeline. Then the TBM is to be attached to lift bags, winch onto a pontoon, and then taken to shore. The carrier is a high-density polyethylene
carrier pipeline, to be pulled through the steel pipe and plugged until brought into service, to prevent any leaks or ground and seawater intrusion. Installation of the full outfall is expected
to the best part of two months. A 66m-long diffuser be installed at the
end of the outfall. It will include 22 rubber nozzles, called ‘duck bills’, designed allow periodic release of treated effluent but no ingress of sea water. Treated effluent will come from the Clarks Beach Wastewater Treatment Plant, currently being upgraded.
Philippines road milestone THE PHILIPPINES - Breakthrough has been achieved on the Davao City Bypass project, involving construction of the first long- distance mountain tunnel in the Philippines. The project involves construction of a
29.7km-long, four-lane road including bridges and tunnels, excavated using the New Austrian Tunnelling (NATM) method. The client is the Department of Public
Works and Highways, and the project is supported by the Japan International Co- operation Agency (JICA). Additionally, the government is building a
further 15.8km portion of the bypass, giving a total length of 45.5km.
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