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This article brings out background information and evidence of a forensic investigation into a massive sinkhole accident in Georgia resulting in two fatalities. Data indicate that soil erosion coupled with a failure in the sewer tunnel built on top of fill soils are the causes of the accident.

The Inland Feeder designed to increase the amount of state-produced water for Southern California comprises of the Arrowhead East and Arrowhead West Tunnels. The tunnels incorporate structural features like impermeable lining, unique seismic sections and extensive probing and grouting to account for earthquakes and a ground-water monitoring program with 100 monitoring sites. The use of thick-walled steel pipes in fault zones serves a means of protection for the tunnel-workers during earthquakes.

The construction of tunnels at the complex Fort Point Channel I-90 portion of Boston's Central Artery Project involves tunnel jacking, deep soil mixing and outsized immersed tube tunnels by the engineers and contractors. Contacts worth over a billion dollars have been awarded for the purpose. The design and construction of Fort Point Channel faces challenges regarding the use of new techniques and weak clay soils

Reinforced rock arch design works on the basis of utilizing a rock's inherent properties to make it work as an arch. The advantages of this tunnel construction method includes reduced construction costs, increased flexibility, improved safety and minimized labor and materials. The final structure consists of the rock mass interacting with the reinforced rock arch to form the tunnel. This interaction stabilizes the structure and limits deformations toward the tunnel opening. Engineers should be able to adapt to specific site conditions to ensure the viability of constructing rock arches.

The Singapore Ministry of Environment was forced to construct a new sewer tunnel as close as possible to the mass transit tunnels since a deeper excavation would significantly increase operational costs. The ministry decided that an underground chamber for the sewer beneath the transit tunnel alignment should be constructed early on the basis of geotechnical studies and risk assessments. The chamber would be built before the rail project so that the tunnel-boring machine for the sewer can pass 2.5 meters below the finished rail tunnels.

Constructors encountered petroleum-hydrocarbon-saturated sandstone during the design phase of the Hilltop Interceptor tunnel project in Cleveland, OH. Engineers from Parsons Brinckerhoff Ohio Inc. used high-density polyethylene as lining material for the cast-in-place concrete shaft to ensure project health and safety and prevent oil seepage into the shaft after completion. Waste material certified not to contain oil was used as fill material while those containing oil were disposed in landfills or treated before discharge to Ohio's sewage collection system.

The Boston Central Artery/Tunnel (CA/T) project aims to decongest Boston's roads and improve its surrounding areas. The construction of an immersed tube tunnel in Boston Harbor, which constitutes a part of the CA/T project, poses many challenges to its engineers and designers. The tunnel installation involves steel fabrication, trench excavations, blasting and dredge material disposal. Construction management takes into consideration the project's effects on Boston Harbor and time management is used to minimize disruption of the harbor's activities.

The A86 Duplex is a 10 km long bilevel tunnel that can accommodate up to three lanes of traffic in each direction. The tunnel will complete the Paris ring road by 2010 and was designed to accommodate only passenger cars and other light vehicles. It will be constructed of reinforced-concrete segments with 30 mm thick walls and will have escape passages located every 200 m.

Investigators from the National Transportation Safety Board (NTSB) concluded that the use of an epoxy anchor adhesive was the cause of the collapse of 10 ceiling panels in the D portal connecting Interstate 90 in Boston to the Ted Williams Tunnel, which is part of the Big Dig project. The NTSB raised issues on how the epoxy came to be used and why inspections were not carried out even after signs of displacement or 'creep'.

The high-performance of tunnel boring machines used by Jay Dee Contractors increased the construction speed of Little Calumet Leg, the final part of Chicago Tunnel and Reservoir Project (TARP). The constructional details of tunnel are presented along with the specifications of the tunnel boring machine.

A 6,280m long Hai Van Pass of Vietnam the longest highway tunnel in Southeast Asia, which is opened on June 5, is discussed. The tunnel has a cross sectional area of 73meter square and will carry daily traffic.

King County issued bid application deadlines in September 2005 for the construction of first of three tunnel sections that form Brightwater Wastewater Treatment Plant (WWTP). The three tunnels will measure 13 miles and is expected to start construction in late 2006.

The construction on a pair of tunnels that would transfer water between two sources as part of a larger project to provide high-quality drinking water to more than 750000 residents in the area of Vancouver, British Columbia is described. The tunneling project would begin with a 185 m deep vertical shaft at the Seymour end.

The Massachusetts Water Resources Authority (MWRA) proposes to build a tunnel to collect excess sewage from the Boston waterways. The proposal is intended to eliminate combined sewer overflows at a number of poplar beaches located along Boston's North Dorchester Bay.

The Channel Tunnel Rail Link (CTRL), connecting the Channel Tunnel with London, will significantly decrease travel times between London and continental Europe when it is completed in 2007. In designing the project's tunnels, engineers have made advances in such areas as the large-scale use of fiber reinforced precast-concrete linings and the design of shotcrete linings.

This article discusses the restoration plans for the Peruvian andes following destruction of the hydroelectric power plant and debris collection from the floods. Design and construction of a high-profile tunnel from the right side of the valley through rock face into the river and then through rock on the opposite side of the valley to a reception shaft is described.

The largest diameter tunnel in North America is planned to be built by the Metropolitan Transportation Authority of Los Angeles County in order to provide a freeway to the commuters. Details of the two tunneling techniques intended to be used for the proposed project are presented.

The world's largest tunnel-boring machine will be used by Ontario Power Generation, Toronto, for tunnel construction on the Niagara River. Details of the tunnel are presented. The tunnel will convey water to the Sir Adam Beck power generating complex in Ontario.

An analysis of how knowledge and technical expertise of small engineering firms helped the construction of the $14-billion Boston's Central Artery/Tunnel, also called the Big Dig, is presented. The small firms provided technical expertise on urban design, architecture, and traffic management to large engineering firms.

The King County Department of Metropolitan Services is constructing a soft-ground tunnel to divert wastewater for secondary treatment and store storm-water overflows in the West Seattle drainage basin, WA. Site constraints, geology and construction issues affected the design of the 10,200-foot project, which will divert dry weather sanitary flow and store excess flow during wet weather at the Alki plant, Seattle.

Tunneling operations for the North Huron/Rouge Valley Wastewater Control project in Wayne County, MI, revealed a range of soil conditions that will make progress difficult. The project's contractor, joint venture Kajima/C.J. Rogers, adopted a method that combined an automated tunnel-boring machine (TBM) with a manual TBM for the pipe-laying process. The wastewater facility is the first phase of a three-part sewer project for Wayne County, MI, and will connect far-flung areas like Dearborn to Detroit's sewage facilities.

The Central Artery/Tunnel in Boston, MA, an $8 billion project which is being handled by four companies, was the topic discussed during the Geo-Institute conference. The project designers showed that plans are carefully laid to balance the construction cost without putting the project at risk. Several problems regarding the project such as constructing the tunnel in an urbanized area and construction site's stability were raised and possible solutions were presented. Other related topics such as geophysics and spatial analysis in soil and landslides were also dealt with in the conference.

Construction work has just started on a 25 ft diameter and a 200 ft long starter tunnel for the Exploratory Studies Facility (ESF) at Yucca Mountain, NV. Scientists will study the ESF's viabilityas a permanent storage site for spent nuclear fuel and radioactive waste. The starter tunnel will house a tunnel-boring machine which will excavate additional tunnels for the ESF. The ESF will have a U-shape design with a 1-mile north entrance ramp, a 2-mile south exit ramp and a main 2-mile cross tunnel at a depth of 1,200 ft below ground surface.