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By Kenneth Pidgeon

The Boston Marine Industrial Park (BMIP) Boat Section, which is part of contract C04A2 of the Central Artery/Tunnel (CA/T) project, is currently under construction in South Boston, Massachusetts (Fig. 1). The Boat Section is approximately 900 feet long and varies in width from about 135 to 185 feet (Fig. 2). The depth to the top of the Boat Section base slab varies from about 28 to 31 feet below final ground surface and about 23 to 26 feet below normal ground water levels. The Boat Section is supported on 578 anchors drilled into the underlying bedrock each designed for a working load of 630 kips. Design and Construction Team The owner of the project is the Massachusetts Highway Department (MHD). The owner's representative is the Management Consultant, Bechtel/Parsons Brinckerhoff. The section design consultant (SDC) consisted of HDR Engineering, Inc. with GEI Consultants, Inc. as the geotechnical subconsultant. The general contractor was the joint venture of Kiewit, Perini, Atkinson, and Cashman. The boat anchors were installed by the subcontractor Delta Geotechnical Services, Inc.

Jan 1, 1994

By Robert L. Parsons

This paper describes the results of a detailed analysis of a loess deposit at the deep foundations test site established by the Kansas Department of Transportation. Multiple CPT, SPT, and pressuremeter tests were conducted as part of the investigation. This paper includes an evaluation of the effectiveness of common correlations used with the CPT, SPT when used for classification of loess and estimating its properties. Results show that common correlations must be used with caution as significant errors in estimation may result from using methods developed for other soil types. Laboratory testing included direct shear, triaxial, collapse, and consolidation testing, with many of the tests conducted on both vertically and horizontally oriented samples to evaluate anisotropic behavior. The results showed that strength properties could be considered to be isotropic.

Jan 1, 2009

By Franklin M. Grynkewicz

As part of the Boston Harbor clean up project, the new 1,000 mgd Deer Island Sewerage treatment plant includes ten 240 feet high egg-shaped "residuals" tanks. Contract documents called for these structures to be supported on 2,600 sixteen inch concrete filled pipe piles. The project site is underlain by highly variable glacial and marine deposits. Subsurface conditions vary from one extreme where firm glacial deposits exist at subgrade to the other extreme where 70 feet of medium stiff clays overlying weathered bedrock must be dealt with. The most common profile consisted of 15-20 feet of sands, 20-40 feet of marine clays, and 20-60 feet of stratified glacial deposits (commonly called tills) overlying Argillitic bedrock. Post bid redesign work, initiated as a cooperative effort between the owner and the general contractor, demonstrated that an $8 million savings could be realized if high capacity 48 inch diameter caissons replaced the specified pipe piles. A highly unusual arrangement of having the general contractor and specialty subcontractor providing input to the owner's engineering team allowed the redesign work to proceed on a "fast-track" schedule.

Jan 1, 1992

By Abolfazl Eslami, Fatemeh Rostami, Sara Heidarie Golafzani, Mohammad Arabameri

Collapsible loess is classified as problematic soil found in most continents. The loess immediately collapses under stresses induced by axial compressive loading or the soil weight when exposed to moisture. In Iran, vast areas of the Golestan province are covered with aeolian loess deposits. This paper investigates whether the simultaneous effect of inundation and pre-loading in helical pile installation are operative and effective in improvement of Golestan loess. The effect of installation conditions on loess collapsibility is studied via two main approaches, i.e., field investigations and physical modelling. The experimental studies include installation of eight single helix piles in the Amirkabir University of Technology Frustum Confining Vessel, i.e., FCV-AUT. Also, four single helix piles with embedment depth of 3 m and diameter of 250 mm were installed in Golestan province and full-scale pile static loading tests were performed. The results indicated that the simultaneous application of crowd loading and water pressure during installation of helical piles results in better soil shear strength parameters. Moreover, high crowd stresses or low crowd stresses accompanied by water pressure during pile installation brings about similar load-displacement behavior of model piles installed in FCV-AUT and full-scale helical piles.

Oct 1, 2022

By Richard F. Sliwoski

The Virginia State Capitol was designed by Thomas Jefferson and constructed in 1785. The Capitol is of great historic and architectural significance to not only the Commonwealth of Virginia but to the nation. It is the oldest operating Capitol in the U.S. and required a total restoration/renovation as well as an expansion to continue to remain functional. Site conditions dictated that the expansion (a new visitor center) be placed underground on the south side of the Capitol building, requiring a 40-foot deep excavation approximately 5 feet from the Building. Because of its historic significance, every measure had to be taken to ensure the safety and function of the Capitol during construction. The construction techniques that were used to make the deep excavation and protect the historic Capitol included a tied back concrete slurry wall, jet grouting, compensation grouting, and instrumentation monitoring. This paper describes the history of the Capitol building, the techniques that were employed for construction of the deep excavation, results of the latest movement monitoring, and factors contributing to meeting the restrictive movement goals.

Jan 1, 2006

By David White

When finished (projected completion in 2016) the Hong Kong-Zhuhai-Macau Bridge Project will comprise three cable-stayed span bridges and a 4.15 mile immersed tube tunnel - linking Hong Kong to Macau and the mainland Chinese city of Zhuhai. The design included two artificial Islands to serve as the transition structures for the tunnel to bridges, entailing a massive seaborne land reclamation project, and the use of thousands of sheet piles, and man-hours. The challenges of driving individual steel sheet in 100? of water are well known, let alone in the open waters of the South China Sea. In 2010 a joint effort between American Piledriving Equipment (APE) and Allnamics Pile Testing Experts convinced the Chinese contractor First Harbor Marine Group China that a massive multi-vibro hammer can be used to drive 130? long, 72? diameter steel pipe piles weighing 662 US tons each into the sea bed of the South China Sea for the Hong Kong - Zhuhai - Macau bridge artificial islands. Combining APE?s hammer design, production and operation know-how with the pile driving simulation and installation know-how of Allnamics made it possible to show the feasibility of driving these gigantic piles into bottom of the sea to the required depth.

By Frances Badelow

This paper describes a design process for piled raft foundations supporting high-rise buildings. The design process comprises an initial stage of geotechnical site characterization using the results of investigation boreholes to prepare a subsurface model and derive geotechnical parameters for raft and pile design from empirical correlations. Following this a preliminary analysis is undertaken using a combination of elastic theory and allowances for non linear behaviour of the piled raft system to assess the viability of such a foundation system and any potential advantages of a piled raft over conventional fully piled foundation systems. Finally, a detailed analysis is undertaken using the GARP8 computer program. Case studies where this design process has been successfully used to design a more efficient piled raft system that has resulted in significant cost and time savings compared to conventional bored pile foundation options are also described.

Jan 1, 2006

By Jr. D'Angelo, Michael M. Blendy, Shawn Downey

"A grouted helical pile was used to support new buildings in the reconstruction of a large residential development. Foundation options were complicated by urban fill underlain with variable alluvial soil. A driven timber pile and grade beam system was recommended to support the new buildings. Other foundation options are also discussed. The grouted helical pile was quoted as an alternate and ultimately won the bid based on the economics and performance of the system. Data from 8 load tests was used to develop an empirical site specific relationship for determining pile capacity based on both installing torque and installation depth. Design to incorporate tolerance on installed pile location is presented. With the three phases completed, 554 residential dwelling units supported by 3645 grouted helical piles had been constructed covering 18 city blocks on the 44 acre site. IntroductionThe Philadelphia Housing Authority reconstructed the Tasker Homes housing complex located in southern Philadelphia, Pennsylvania, adjacent to the Schuylkill Expressway in the Grays Ferry area. Keating Building Corp. and Pennoni Associates were the general contractor and the structural engineer respectively. The original Tasker Homes development was constructed from 1940 to 1941 and consisted of 44 acres of primarily two and three-story residential brick buildings. These buildings were supported by a timber pile foundation system. The structural condition of the buildings supported on the timber piles was generally good in comparison to areas outside the buildings. These areas had settled possibly up to 2-feet in places due to the heterogeneous nature of the urban fill."

Jan 1, 2005

By Andres M. Baquerizo, Jeremiah J. Filjones, Nicholas Feldt

The Estates at Acqualina located in Sunny Isles Beach, FL, is comprised of two, ocean-front, 50-story, luxury towers with podiums and villas. With city regulations now requesting that above-grade floors be limited to commercial or residential units, parking facilities for the tower structures were situated within two levels of underground basement parking. However, ensuring dry excavation through south Florida’s highly pervious limestone, immediately adjacent to the beach where the groundwater table is very shallow, can be extremely challenging and costly for developers. In recent years, significant advances have been made to overcome this challenge with the innovative use of deep soil mixing to create a “dry hole”, assisting in the construction of foundations and underground usable space for parking, storage, etc. The “dry hole” system includes a soil mix bottom seal, with soil mix secant pile walls in combination with auger cast deep foundation elements to support the future structure. This approach enables groundwater control to greater depths than can be achieved by conventional sheetpiling and dewatering. For the Estates at Acqualina, a successful turnkey, design-build joint venture between two foundation and geotechnical contractors resulted in a dry excavation to 34 ft (10.4 m) below grade and to a record- breaking auger cast pile depth of 182.3ft (55.6 m), all within an aggressive 26-week schedule to deliver the “dry hole” excavation for the first tower. This presentation will discuss the logistics, quality control, design, and safety for the different techniques involved. INTRODUCTION AND BACKGROUND The Estates of Acqualina is a pair of 50-story luxury towers located on Sunny Isles Beach in Florida with a two-level underground basement for parking. The project’s location just steps away from the Atlantic Ocean, geology, and high-water table created a challenging project. The owner, Trump Group, contracted the joint venture of HJ Foundation and Hayward Baker (HJ/HB) to design-assist-build a system to control the groundwater, allowing the 2-story underground parking structure to be constructed. In order to accomplish this task, the JV utilized an installation technique known as deep soil mixing. This technique mixes the in situ material with a cement slurry to create a very impermeable material called “soilcrete”.

Jan 1, 2019

By Deshmukh A. M.

Existence of human beings and their relationship with the nature is symbiotic. The lack of perspective and negligence of nature disturbs the equilibrium of environment and causes unprecedented disasters. Geotechnical engineers are directly concerned with hazards of nature as elements of foundation and of nature are inter related. Rational design and construction of foundation can be accomplished only after properly assessing influence of environment This paper briefly delineates impacts of environment and human activities and presents salient features of management of impacts through the system of deep foundation. Limitation of negative effects and enhancement of positive developments necessitates eco-consistent planning of engineering projects based on the geotechnical aspects of environmental impact management.

Jan 1, 1996

By Rouzbeh Afsharhasani, Moses Karakouzian, Brandon Kluzniak

"The Vegas High Roller is the centerpiece of a new development parcel adjacent to the Las Vegas Strip. At a height of 550 feet, the High Roller is currently the tallest observation wheel in the world. The design team conducted a geotechnical site investigation to characterize the alluvial soils and cemented layers encountered and to provide foundation design recommendations for the observation wheel, boarding platform, and temporary structures needed to erect the wheel structure. This paper presents a case history of the geotechnical design process, including development of a ground model and design parameters, high-strain dynamic axial load tests, and settlement monitoring during construction. Results indicated that design parameters were conservatively assumed and that the majority of the axial load was transferred to a near surface caliche layer, thereby resulting in insignificant settlement of the foundation system.IntroductionThe engineering of the Vegas High Roller is similar in concept to that of the London Eye and the Singapore Flyer. The wheel has 28 cabins, each with a capacity of 40 persons. The top point of the structure is 550 ft above ground level at the site.A geotechnical site investigation program was undertaken and subsequent analyses were performed to provide foundation recommendations for the observation wheel legs, boarding platform columns, and temporary structures directly associated with construction of the observation wheel."

Jan 1, 2017

By Mohammed Z. Islam

As cities are growing all over the world, the need for urban transportation facilities are on the rise. Designers (of these facilities) today are faced with a number of constraints for their design, of the most is the space limitation and impact of new construction activities to the community. A typical subway station, as the focus of this paper, is approximately 600 to 1000 feet long, 50 feet wide and 2 to 3 story high. With such a large volume of construction activities, it is easily realized why underground stations are becoming obvious choice for larger cities eventhough the cost could be 2 1/2 to 3 times as much as an aerial station and 4 to 5 times that of an at-grade station [O'Neil et. al.(1977)]. Since cost is an important factor which is always increasing, therefore, the designer should have a good planning, consider alternatives for design and come up with a realistic design with minimum impact to the community. This paper is about the geotechnical considerations that the designer should be aware of. PLANNING A 1977 report [O'Neil et. al.(1977)] on the construction costs for a number of underground subway stations indicate that about 4 0% of the cost is site-controlled, 35% is structural items, and 25% is finish and equipment. It is seen that of opportunity exists for cost savings in the site selection and proper use of the site. Once the site is selected, the cost of construction become controlled by urban conditions at the site, geotechnical conditions, station size and depth. Therefore, the design-solution is very much site-specific. The geotecnical designer should collect the following information at the early phase of the design:

Jan 1, 1993

By Dale Berner, Michael O’Sullivan

"This article focuses on lessons learned from innovative designs including in-the-wet construction methodology and modified foundation conditions, for two United States Army Corps of Engineers (USACE) megaprojects. Olmsted Dam FoundationThe over $2 billion Olmsted Dam on the Ohio River is currently under construction 16 mi (29.6 km) upstream from the confluence with the Mississippi River. The project is under the jurisdiction of the Louisville District of the USACE. It will consist of an 800 ft (244 m) long tainter gate section, a 1,400 ft (427 m) navigable pass, two boat abutment sections, a fixed weir section, and upstream and downstream scour protection. The Olmsted Dam and its two 1,200 ft (366 m) locks, which were built in 2002, will eventually replace both Locks and Dam #52 and #53, both built in 1929, and thereby bring significant benefits to the Ohio River navigation system.In 2002, the Jacobs/COWI JV completed the design of the dam; which was an engineering challenge for several reasons. A significant consideration was its proximity to the New Madrid Fault, which could impose an 8.4 Richter scale seismic event on the structure, which is located in an area of potentially liquefiable alluvium. The extensive seismic analysis performed by the designer included a response spectra analyses, lateral pushover analyses of pile foundations, hydrodynamic added masses, pile group effects, and the development of kinematic motions as a result of the soil-pilestructure interaction."

Jan 1, 2016

By Robert B. Bittner

The Sutong Bridge across the lower Yangtze River in China will have, when completed, the longest span (1,088 m) and the highest towers (306 m) of any cable stayed span in the world. The foundations for this record setting span will also be record setting. They are located in water depths exceeding 30 m with maximum flows exceeding 3 m/sec. The soil at the site of the main pylons consists of layers of silty sands and silty clays extending to bed rock at 270 m below river elevation. This paper describes the innovative methods used by the team of foundation designers and constructors to support this record setting bridge at this very challenging site. This paper covers three specific topics related to the foundations of the Sutong Bridge: ? Design and construction of the 131 drilled shafts (2.8/2.5 m diameter and 114/117 m long) under each of the two main pylons, including the post-grouting of all drilled shaft tips. ? Design and construction of the scour protection for the two main pylons. ? Construction methods used to construct the waterline pile caps (113.8 m by 48.1 m by 13.3 m deep) under each pylon.

Jan 1, 2007

By Robert Alperstein, Nidal AbiSaab, Joe Pastore

"This paper describes the design and construction aspects of the foundation support for a 57-story building currently under construction in lower Manhattan. The site is located near the East River with subsurface conditions consisting of about 40-ft [12.2-m] of unsuitable historic fill and soft plastic clay underlain by about 130-ft [39.6-m] of dense sand resting on bedrock. A mat foundation supported on unsuitable soils improved by jet grouting was selected for the project. Design concepts and selection of the engineering properties of the improved and natural foundation soils are discussed. The results of quality control testing and methods to verify design parameters during construction are presented.INTRODUCTIONNew York City (especially Manhattan) is known for its skyline of high rise structures. The geologic conditions in the New York Metropolitan Area influence the selection of foundations and feasibility of high rise construction as noted by Horvath (2013). These conditions include varying depth and quality of bedrock, multiple glacial events during the Pleistocene Epoch, and the effects of human modifications to the subsurface environment. Clusters of relatively taller buildings are generally located in Lower and Midtown Manhattan where sound crystalline bedrock is at relatively shallow depth beneath the ground surface and shallow foundations rest on the bedrock surface. In recent years the use of more costly high capacity driven piles or drilled caissons and deep basements has enabled the high skyline to spread to other areas."

Jan 1, 2016

By Charles M. Wilk

"Mass stabilization involves mixing binding agents into marginal or contaminated soil to improve the subject material’s physical and/or chemical properties. This paper concentrates on the principles of soil mixing and benefits and application to new and existing rail right-of-way. Successfully applied in Scandinavia and other European countries, the soil mixing is now being applied in right of way in the northern latitudes of the U.S. and Canada. These regions have significant areas of “peaty” soils that can complicate construction and maintenance of rail and structure foundations. Mass stabilization can be used to improve the bearing strength of these soft soils for subsequent construction of railroads, pipelines, roads, and buildings. In civil engineering, the technology is often used to improve the construction properties such as bearing strength, of a marginal soil. In environmental engineering, stabilization is remediation treatment technology that protects human health and the environment by immobilizing hazardous constituents within the treated material. . The treatment is conducted while the subject material remains in-place (insitu). Mass Stabilization is often used to accomplish both civil and environmental purposes on the same project effectively addressing marginal soil while eliminating the expense of soil removal and replacement.This paper presents the principles of mass stabilization technology, implementation in the field and recent completed railway projects.The example rail projects will present the various benefits that soil mixing provides to railway construction and maintenance. Bench-scale studies and full scale implementation as well as soil construction properties before and after mass stabilization will be discussed. The paper and presentation will include information on the advantages of mixing methods and binding agent delivery systems.INTRODUCTIONNew or existing railroad right-of-ways may cross ground with low bearing capacity. Right of way subgrade undergo deflection (strain) as loads (stress) are applied (1). The amount of strain or deflection of the subgrade caused by loading of a train is proportional to the stiffness of the subgrade materials. Some soils, such as tamped ballast, are very stiff and resist loads well. Other soils such as soft clay, peat, or loose sand have low stiffness and undergo substantial movement under loads. It is very desirable to have the stiffest possible material in a track subgrade. Stiff subgrade material limits deflection under load, reducing track roughness and occurrence of track defects. Mass stabilization is a geotechnical method that can be used to improve the bearing capacity or stiffness of soil in these right-of-way. Mass stabilization involves mixing binding agents into soil subject to treatment while the soil remains in-place or insitu. Variations in the design or areas subject to treatment can be used to address transmission of vibration to adjacent structures."

Jan 1, 2017

By John L. Walkinshaw

It is obviously not possible in the time given me today to review in great detail all the research of the past 20 years that the (FHWA) has sponsored or participated in. In this presentation I will highlight some of the principal programs that I am familiar with. This handout lists practically all the reports prepared for the FHWA involving deep foundations and some related work involving the same structural elements (piles, shafts, ground anchors).

Jan 1, 1993

By Andrew Port, Ali Ghandeharioon

Nonlinear seismic deformation analyses using the finite difference program FLAC were performed for a wastewater treatment plant to estimate foundation displacement and performance of two proposed trickling filters during the 2475-year event design earthquake. The effective stress based constitutive model UBCSAND, which captures the cyclic behavior of both the “sand-like” and “clay-like” materials, was used to model the dynamic response of the soil strata. Dynamic analyses of the site indicated that in absence of ground improvement or deep foundations beneath the proposed trickling filters, those structures would undergo horizontal displacements in excess of 1 m and short-term differential settlement gradient of about 400 mm over 50 m as a result of seismic and post-seismic settlements. Three mitigation options were considered for limiting the seismic displacements and differential settlement gradients of the proposed trickling filters. These alternatives include vibro-replacement stone columns, vibro-replacement stone columns plus supplementary cutter soil mixing (CSM) configurations, and pile foundations. Various layouts for each mitigation option were considered including the lateral extent of the ground improvement, CSM walls and pile spacing. Seismic horizontal and vertical displacements of the proposed structures as well as post-earthquake consolidation settlements due to dissipation of excess pore water pressures in soil layers were assessed in all the analysis alternatives. The analyses indicate that all the alternatives considered have the potential to provide a comparable level of seismic and post-seismic performance. However, for similar performance levels, the ground improvement options need to extend well beyond the edges of the proposed structures, while the piles can be limited to just beneath the footprint of the structures. INTRODUCTION Annacis Island Wastewater Treatment Plant (AIWWTP) is owned and operated by Greater Vancouver Sewerage and Drainage District and services a population of approximately 1 million people in Vancouver, British Columbia. Wastewater is generated by residential, commercial, and industrial sectors and the treated effluent is discharged to Annieville Channel of Fraser River on the south side of Annacis Island. AIWWTP is located on a 51-hectare site and was commissioned in 1975 as a primary treatment plant, but has had two major expansions to meet the population growth needs, and to improve the treatment process efficiency through the provision of secondary treatment of the liquid stream. The current expansion includes construction of additional solids contact tanks and secondary clarifiers. Future expansions include the construction of proposed additional trickling filters. New expansion structures are required to be designed for post-seismic operation after the 2475-year event design earthquake.

Jan 1, 2018

By Thang V. Nguyen, Lisheng Shao, Gary E. Taylor

"The Community Memorial Hospital of Ventura, California, proposed to build a new state-of-the-art Cancer Treatment Center with radiation shielding walls and roof. The loose silty soils at the site had the potential to liquefy during an earthquake, which would result in significant settlement under the heavy footing loads. Treatment options included various deep foundation alternatives, as well as several ground improvement methods. The choice of wet soil mixing minimized the disturbance to the adjacent hospital during construction and potential settlement. Wet soil mixing allowed the structure to be supported on a raft foundation, meeting the stringent building total and differential settlement criteria. The authors also performed unit cell 3-D finite element analyses to evaluate the behavior of the wet soil mixing system in seismic loading conditions. This paper highlights the ground improvement design, construction, QA/QC, and the research related to evaluating the effectiveness of soil mixing for liquefaction mitigation.INTRODUCTIONThe Ventura Community Memorial Hospital proposed the construction of a new Cancer Treatment Center to replace the existing structure, which was built in 1901. The hospital complex is located in a wellestablished residential neighborhood. The soil conditions at the site of the proposed structure required ground modification to support the very heavy radiation treatment section of the building and limit settlement. Originally, 90-foot-long precast piles were considered for foundation support. Based on supplemental Cone Penetration Tests (CPTs) performed, the deepest CPT did not encounter competent pile bearing strata at a depth exceeding 30.5 m (100 ft). This could result in failure of the piles under long-term conditions, especially if hydro-consolidation occurs. The more realistic pile penetration depth would have been 36.6 to 45.7 m (120 to 150 ft). In addition, the excessive noise in association with pile driving would have been unacceptable to the community, patients, and staff of the hospital, so an alternative ground improvement solution was required.The specialty geotechnical contractor recommended wet soil mixing, an economical solution of creating a soil-cement product known as soilcrete that would significantly reduce the construction related noise and provide a more complete deep foundation for the structure.SOIL CONDITIONS AND SETTLEMENT CONCERNSThe subsurface soils were interbedded (Fig. 1) consisting of loose to medium dense silty sands, and soft to medium stiff silty clays to a depth of 30.5 m (100 ft). Groundwater was encountered at depths of 9.1 m (30 ft) and historical high groundwater was at 8.5 m (28 ft) below the ground surface."

Jan 1, 2015

By David White

"When finished (projected completion in 2016) the Hong Kong-Zhuhai-Macau Bridge Project will comprise three cable-stayed span bridges and a 4.15 mile immersed tube tunnel - linking Hong Kong to Macau and the mainland Chinese city of Zhuhai. The design included two artificial Islands to serve as the transition structures for the tunnel to bridges, entailing a massive seaborne land reclamation project, and the use of thousands of sheet piles, and man-hours. The challenges of driving individual steel sheet in 100’ of water are well known, let alone in the open waters of the South China Sea.In 2010 a joint effort between American Piledriving Equipment (APE) and Allnamics Pile Testing Experts convinced the Chinese contractor First Harbor Marine Group China that a massive multi-vibro hammer can be used to drive 130’ long, 72’ diameter steel pipe piles weighing 662 US tons each into the sea bed of the South China Sea for the Hong Kong - Zhuhai - Macau bridge artificial islands. Combining APE’s hammer design, production and operation know-how with the pile driving simulation and installation know-how of Allnamics made it possible to show the feasibility of driving these gigantic piles into bottom of the sea to the required depth.INTRODUCTIONThe challenges of driving individual steel sheets in deep water are well known, let alone in the open waters of the South China Sea. Often the challenges of construction are overcome with engineering or equipment. The challenges of China’s Hong Kong-Zhuhai-Macau Bridge, on the drawing board since 1983, were to overcome both. The challenges of overcoming the skepticism of the Chinese Engineering community would be another story.The finished project will comprise three cablestayed span bridges and a 4.15 mile immersed tube tunnel linking Hong Kong on an eastern span to the China mainland cities of Zhuhai and Macau via two western spans."

Jan 1, 2017