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“SolarWindow is attempting to make history by developing what may be the single-biggest breakthrough in the clean energy industry in a long time,” says John Conklin, president and CEO of SolarWindow Technologies, when referring to the company’s vision of an electricity-generating window.
As the seventh-largest state in the US by area, Nevada needs its roads. And the largest freeway construction project in the state’s history is currently underway.Called Project Neon and commissioned by the Nevada Department of Transportation (NDOT), the undertaking covers a 3.7-mile corridor through the heart of Las Vegas and will cost almost $1bn in total. It includes the approach spiral Interstate 15/US Highway 95 interchange — otherwise known as the Spaghetti Bowl — where around 300,000 vehicles pass through daily, conducting 25,000 lane changes every hour.Design lead on the project team is Atkins, who are managing all design and engineering services, including the project’s Active Traffic Management System (ATM). This is key to realising the NDOT’s overall construction plan, which prioritises safety and driver awareness.It involves keeping motorists informed with real-time information and updates — before, during and after the construction of the freeway project. Atkins has previous experience with this type of technology, having designed freeway management systems for more than 80 miles of roads in Southern Nevada in the past.The dynamic message signs positioned over the freeways provide information on alternative routes, any traffic incidents and restrictions, and instructions regarding lane control and variable speed limits.The project is indicative of more than one current trend in the road construction sector, says Atkins.“As a design, engineering and project management consultancy, we have seen an increase in the use of public-private partnerships (P3) to fund and operate projects, as well as an increase in design-build as the method for project delivery,” says Barry Schulz, chief operating officer for Atkins, North America.
Adding capacity to the over-tasked wastewater system in Mexico City, an alignment through changing ground conditions is a likely candidate for Robbins’ Crossover TBM, Nicole Robinson reports.In the mountains northwest of Mexico City, the soft rock is self-supporting and very consolidated, a dream to mine. "Even the face is self-supporting," says Roberto Gonzalez, Robbins' general manager in Mexico. "You could use a normal backhoe and excavate like that. It's a beautiful ground to bore."But the alignment crosses valleys of tuff, faults and finishes with a stretch of soft ground with low cover. This is the scenario for Túnel Emisor Poniente II (TEP II), or the English translation of West Drainage Tunnel II.Conagua, Mexico's national water commission, is building the 5.9km-long tunnel with a 7m i.d. to reduce flooding in the area, and increase wastewater capacity. Across three municipalities, some 2.1 million people will benefit from the tunnel project.The contractor joint venture of Aldesa, Proacon and Recsa chose an 8.7m diameter, dual-mode type machine capable of "crossing over" between rock and EPB. With the August 2015 tunnel boring machine (TBM) launch on TEP II, manufacturer Robbins has supplied its first Crossover machine in Mexico.End gameRobbins draws comparisons to the Kargi Kizilirmak hydroelectric project in Central Turkey. The design of the TEP II machine was based largely on experience from past projects, and that TBM in particular. While initial reports on the Turkey project showed fractured hard rock, Robbins explains, within 80m of launch the geology became substantially more difficult than expected, consisting of blocky rock, sand, clays and water-bearing zones. The machine required multiple bypass tunnels and major modifications before it could resume excavation.Robbins says these modifications proved instrumental to the design of its Crossover TBMs, including the TEP II machine.In Mexico, the contractor JV expects to convert the machine from hard rock to EPB mode due to changing ground conditions in the last kilometre of the alignment. "Initially the proposal was a hard rock machine but they found they have 800m of water-more EPM conditions-that's the reason we proposed a Crossover," explains Javier Alcala, job site engineer for Robbins on TEP II.The ground conditions at TEP II are complex, from competent to weathered volcanic rock to clay, and sand. The final 800m is also the portion of the alignment with the lowest cover, some 12m, and the most populated. This is one of the reasons for using a Crossover machine. The rest of the drive has between 50-60m of cover on average with some stretches up to 150m."We try not to convert unless it's completely necessary because you stop, you have to drain the screw conveyor inside the machine, and you have to make a lot of changes, for example on the cutterhead," Robbins' Gonzalez explains.As an open mode machine boring in rock, the TBM is equipped in the event of entering running ground, he says. "These closure doors are able to maintain the material in the cutting chamber. They're just a safety." In smaller valleys of tuff there is potentially some water, but it's unknown for now, he explains."For these cases we believe that these closure doors will be held to see what we have to do with the material, if we have to consolidate in the front."Tight fitAldesa's Castillo says one of the biggest accomplishments on the project so far has been organising the logistics in such a small work space-fewer than 10,000 sq m. The JV excavated a 30m deep launch shaft supported by 800mm-thick Milan walls (slurry walls), and used on-site first time assembly, he says, to start excavation as soon as possible.Once assembled by gantry crane, the machine bored 100m before adding back gantries. When completely assembled the machine has nine gantries for a total length of 1,030m.At the time Tunnels & Tunnelling visited the project, the crews were still adjusting to having the full machine in operation, and had only recently started using the continuous conveyors for muck.The TBM was mining through a transition zone between tuffs and dacites, and had excavated 435m by mid November 2015. At the time of publication the TBM has bored 1,417.5m, which equates to 945 rings. The best day has seen an advancement of 42.8m and the best week is 185.1m. Robbins' Mexico office reports the TBM has reached softer geology and is boring very well.Tunnelling is expected to finish within this year and a second lining of reinforced concrete will be installed following excavation to extend the life of the tunnel. "Once we arrive to the final bit, it's a very close curve of 400m radius," Alcala explains.The tunnel alignment ends along the rivers of San Javier and Xochimanga in Atizapan de Zaragoza.
Repairs are finished for giant TBM ‘Bertha’. Patrick Reynolds reports on the two-year-long process.Bertha, better known as Big Bertha, is a 57.5ft (17.53m) diameter tunnel boring machine (TBM) built in 2013 for the Washington State Department of Transportation’s (WSDOT) Alaskan Way Viaduct Replacement tunnel in Seattle, a JV between STP and local firms Frank Coluccio Construction and Mowat Construction, and also HNTB Corp and Intecsa-Inarsa.The machine, built in Japan by Hitachi Zosen Sakai, broke down after an alleged encounter with a steel pipe, damaging several cutting blades, taking two years to fully repair it.By the beginning of 2016, the giant TBM Bertha in Seattle is expected to restart boring on the delayed, central waterfront section of the USD 3.1bn Alaskan Way Viaduct Replacement project, following repairs to the machine.To prepare, Bertha has been undergoing an unusual, if not unique, experience for any TBM, not least the world's largest: she is being buried to commence boring.A 120ft- (36.5m-) deep shaft was constructed to reach the TBM, allowing its vital front section to be brought to the surface for repairs. Following the work, the TBM was reassembled, the cutterhead was turned and other no-load tests were completed. The last task is load testing to relaunch the TBM for its drive below the viaduct.To that end, the shaft has been backfilled with sand and controlled density fill, allowing Bertha to bore once more. Slowly. For a few hundred feet only, at first.Even though the TBM was first launched two-and-a-half years ago, it still has most of its relatively short, 1.7mile- (2.7km-) long tunnel drive yet to finish.The TBM was stopped in a ‘safe haven’, which is a pre-planned, jet-grouted zone designed to allow last checks and adjustments before Bertha bored below the elevated highway again.Fortunately, perhaps, the troubles that brought Bertha to a halt in late 2013 occurred shortly before the machine moved under the seismically-weakened viaduct. Performing a TBM recovery under the viaduct could have been much more difficult. Even outside that zone, the investigation and repairs undertaken presented “a significant challenge”, says Chris Dixon, project manager with Seattle Tunnel Partners (STP), the designbuild JV contractor comprising Dragados and Tutor Perini.Coincidentally, Bertha is preparing to resume boring around the time when, as per the contractor's original schedule target, tunnelling was to have been finished. Bertha is expected to emerge around the beginning of 2017, according to the latest construction schedule issued in November 2015 by STP. The entire Alaskan Way Viaduct Replacement project is to be finished by April 2018.But while the focus shifts from repairing the Hitachi Zosen TBM, and with the tunnelling industry, the coastal city and the state hoping for untroubled progress ahead, the beginnings of legal fights and insurance liability debates over blame have started.The complex arguments over fault, liability and financial consequences are contested between the project owner —Washington State's Department of Transportation (WSDOT), the JV contractor and TBM manufacturer, and various insurers. Lawsuits have been submitted over recent months.Over the two-year standstill, STP and Hitachi Zosen received no payments from the client related to the TBM recovery costs. STP has only received payments for progress achieved on the many other continuing works, such as around the tunnel portals and concreting of the decks within the tunnel bore so far.But, finally, the project looks set to change gear as Bertha prepares to build the rest of the 52ft (15.85m) i.d. tunnel below the waterfront during 2016.Rise of the TBM optionThe aim of the redevelopment project at the waterfront is to improve Seattle's overall transport and economy. Debate over how to do so ran for years, and a host of studies were performed on realizing a fresh infrastructure vision and removing the seismically vulnerable viaduct on state highway SR99.Back in 2008, the leading alternatives did not include the TBM option, especially to construct a large single tunnel, although all possibilities had had reviews.The long-term vision was to create an 'incredible' waterfront for the city — ideally one with minimal traffic on the surface. Putting as much as possible underground was elected to be the way forward, and the deep bore option became a late stage winner in early 2009.The JV contractor proposed building the tunnel with an earth pressure balance TBM, and aimed to have the tunnel open to traffic before the end of 2015. The owner's contract performance deadline was late 2016 for substantial completion of the SR99 tunnel, with performance bonus and penalties either side of the target.STP hired Japan's Hitachi Zosen to manufacture and supply the EPB TBM. Washington state set up an Expert Review Panel (ERP) to look over key assumptions in cost estimates, identify risk during the construction phase, comment on development of funding sources, and consider the project's schedule.Launch, then stopIn late 2011, construction staging commenced in Seattle and manufacturing efforts got underway for the TBM in Japan. The TBM was assembled in dry dock in late 2012, before it was shipped across the Pacific Ocean to Seattle.Many activities in both Seattle and Japan were on the critical path of the project schedule, the ERP cautioned in its February 2013 report. It issued an opinion that the target launch date of June 2013 was not expected to be achieved.However, the TBM was assembled in Seattle over April-July at the south end of the tunnel alignment, and then formally launched at the end of July 2013.Bertha's 2-mile- (3.2km-) long drive was expected to take about 14 months. In its following report of February 2014, the ERP noted that early operation of the TBM had delivered better than expected performance.The tunnelling plan was to set off slowly. The TBM would stop early to perform planned maintenance and checks at key ‘safe havens’ along the first 1,500ft (457m) of the northward drive before then diving below the elevated highway.By early December, and despite the late start in mid-year, the shield had advanced more than 1,000ft (305m), reaching where it was expected to be against the schedule, the ERP reported. The panel also said the shield had advance more quickly than expected by the project team, and pulled back time against the schedule. But then trouble struck. The machine overheated and progress slowed as “unanticipated and increasing resistance was experienced”, WSDOT reported. The TBM was stopped on December 6, 2013.At that point, as per the contract between STP and Hitachi Zosen, STP was about to take ownership of Bertha from the TBM manufacturer. Hand-off was planned to follow after the first, proving and settling, stage of tunnelling, constructing the tunnel up to Ring No. 200, as WSDOT had noted in a statement on December 5, and Dixon confirms.Investigation and recovery planWith Bertha stopped under cover of 60ft (18.2m), the contractor lowered the high water table around the TBM. Drilling wells to a depth of approximately 120ft (36.5m), water pressure was reduced to enable the TBM crew to safely start inspecting the machine’s excavation chamber in early January 2014. Probe holes were also bored ahead to check for potential obstructions.The investigation of the top 15ft (4.6m) of the chamber revealed a piece of 8in (200mm) diameter pipe — a section of steel well casing — in a cutterhead opening, WSDOT reported at the time.In late January, a programme of hyperbaric interventions allowed inspections into more of the excavation chamber. Many of the cutterhead openings were found to be clogged, which was then viewed as the more likely cause on the mining difficulty and not major obstructions — none of which were found inside or in front of the TBM, WSDOT said in February 2014.Then, as a trial, STP restarted the TBM to build a ring. More high temperatures were recorded, like before the December stoppage. Investigating further, STP found damage to the main bearing seal.Laura Newborn, spokeswoman for WSDOT, has expanded on the initial information, explaining to Tunnels & Tunnelling North America that the well-casing was found inside the material blocking a cutterhead opening."The cutterhead was clogged," she says. "The piece of metal was not blocking the opening."She adds that the metal detected in front of the cutterhead turned out to be the nose of the cutterhead. "There was no metal found in front of the machine," she adds.WSDOT said at the time that the steel pipe found in the cutterhead was a well casing, installed in 2002 and used by geologists to study groundwater flows following the 2001 Nisqually earthquake. The owner added that location of the pipe was included in reference materials in the contract. However, according to JV contractor member Tutor Perini's third quarter-2015 results, presented in its 10-Q filing to the Securities and Exchange Commission, STP claims the steel pipe to be a "differing site condition that WSDOT failed to properly disclose." Tutor Perini added that the Disputes Review Board had said the pipe was a differing site condition, but noted that WSDOT has not accepted the finding. WSDOT's spokeswoman told Tunnels & Tunnelling North America the "root cause of the damage to the TBM is still under investigation."Reach and repairSignificant repairs would be needed at the TBM. The ERP said the stoppage to TBM tunnelling would throw out the project schedule by some months. It called on the client and contractor to stay away from debates over blame and financial liability, and keep their focus on investigating and resolving the technical problems.In its February 2014 report, the panel advised that the contractor be given appropriate time to develop a recovery plan. "Returning the TBM to operation should be everyone's primary objective," it added.During the halt in work, the contractor undertook wider inspections and also maintenance work, including replacing damaged cutter tools. But the discovery of damage to the bearing seal system also called for replacement of the main bearing. With such major works required, it was decided that the TBM could not be repaired underground. The shield had to be accessed from the surface and opened up to retrieve the cutterhead and cutter drive unit. STP developed a recovery and improvement plan, which it believed would allow the repaired TBM to resume tunnelling in March 2015.STP's plan was to sink a large diameter access shaft a little ahead of the halted TBM. The 80ft- (24.3m-) wide shaft was built through much of 2014 and readied to receive the TBM.The dormant machine was restarted in February 2015. It broke into the shaft and came to a rest on a concrete cradle, cast on the base of the shaft. Hitachi Zosen hired a heavy lift contractor to extract the front sections of the TBM, and this was done in late March. Mammoet designed a modular lift tower capable of sliding over the 120ft-deep shaft and repair area.Soon after, in its April 2015 report, the ERP said that while reasons for the TBM problems were not yet clear, and also were subject to ongoing legal and commercial debates, the contractor had been constructively using the stoppage period, adding that STP planned "to apply some lessons learned" from the tunnelling work done up until then. The ERP, through its discussion with project parties, said in its April 2015 report that the recovery plan for the TBM "appears to be viable," adding it was reasonably confident the machine could be repaired.The panel added that STP and WSDOT had shared information — "without direction from WSDOT" — on how to improve the TBM's function. "It appears that many of WSDOT's comments have been considered in the redesign and repair plan," ERP said.WSDOT had formed its own Restart Team to monitor the contractor's work and risk and mitigation efforts. "Fully disassembling and assessing the machine was always the key to determining how long the repairs would take," said Dixon, in mid-2015.Revise and rescheduleThe ERP commented the stoppage was "unusually long" due to the scale of investigation and repairs needed, and the area was a congested urban environment with geotechnical challenges. Working around the core recovery challenge, the contractor examined and re-programmed a number of other tasks for the tunnel, such as manufacturing all of the precast segments needed for the entire tunnel and storing them, ready for use. Other re-programmed construction activities, helping to offset some of the effects of the TBM stoppage, have included, says Dixon: • Completing the underground structure of the south operations building; • Constructing the interior cast in-place concrete roadway structure within the completed portion of the bored tunnel; • Advancing north and south cut-and-cover sections enough for their handover to other works packages; and, • Redesigning M&E systems, installing and commissioning them faster in sections instead of keeping with the original plan of doing everything in one go after excavation is completed. By the time of ERP's report in April 2015, the panel had learned the contractor then expected a later restart of the TBM — in August.It also noted, and as STP and WSDOT have continued to say, the rescheduled completion target cannot be determined until after the TBM has been restarted, has bored again but also has been re-checked at the last safe haven.In mid-July, installation of the new main bearing commenced. But the schedule was pushed back further with TBM restart then pencilled for late November.Hitachi Zosen completed the above ground repair works in mid-August, allowing the heavy sections to be placed back down the shaft for reassembly at the open front end of the TBM. Finally, in late November, the cutterhead was rotated and system checks performed in a "no load" test.With those successes, the access shaft finally could be backfilled. The next crucial step for Bertha are the pitstop checks. All being well, the big bore will proceed below Seattle's waterfront over the coming months.* This is a version of an article that first appeared in Tunnels & Tunnelling.
Lifting in New York poses a unique challenge overseen by high levels of regulations. Quickly-built and tightly-spaced skyscrapers combining with busy streets, problems with electricity supply, and mazes of subways. Now NYC Department of Buildings plans to prohibit the use of older cranes. Will North reports.
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