Tunnels Inside Out: How’d They Do That?

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Tunnels are simply fascinating. Today, traveling to and from work via subway or using an underground railway system are excellent examples, be they tube, subway or metro. Some look mundane, others architecturally awesome. Added to this venue are cycleways, aqueducts, subsurface highways (road tunnels), and the like. Some are doing a bang-up job, although hidden: smaller tunnels that accommodate utility lines and pipelines. Underwater tunnels function as roads; take, for example, the Detroit-Windsor tunnel under the Detroit River that connects to Windsor, Ontario, Canada, for consumerism, commerce and tourism. By sharp contrast, however, in 2012, two tunnels with lighting and ventilation systems suspected of being used for the surreptitious transport of drugs were discovered along the U.S.-Mexico borders – indeed, ‘dark’ tunnels.

Ever wonder how a tunnel is constructed? Well, there are a multitude of determinants. The length of the tunnel, type of rock to be bored for its erection, additional dredging to create space for underwater tunnels, etc. Designers, engineers and earth scientists develop combative strategies and techniques to sustain tunnels, aquaducts and bridges from something as simple as saltwater damage to seismic events. Studies are conducted to determine liquefaction in high seismic shock regions that will render both predicted and observed structural displacements to assist in designing tunnels that can withstand deformity.

Boring Machines and Linings
Beside from thermo nuclear machines that can bore through concrete, there is a more popularly used one – very simply, a tunnel boring machine (TBM). It is an alternative to drilling and blasting methods in rock and conventional “hand mining” in soil. TBMs have the advantages of limiting the disturbance to the surrounding ground and producing a smooth tunnel wall. This significantly reduces the cost of lining the tunnels, and makes them suitable to use in heavily urbanized areas. TBMs also are utilized as shields when a tunnel is bored through softer materials like sand, slit or clay, or other geology is present that may compromise the tunnel. Shielding was initially designed as a safety net to protect tunnel workers from cave-ins, but the TBM shield process also keeps the tunnel open for the lining process. Linings are then erected with the use of the TBM. Pre-cast concrete segments; cast-in-place concrete; permanent cast iron; cast steel segments; pipe in tunnel; or Shotcrete lining (temporary or final) are utilized for linings, and gradually, the tunnel’s lining replaces the shield as permanent tunnel wall.

The Tunneling Industry in California
The public sector is the prime contractor, while there is some private sector work (e.g., wine caves, tunnels, and alternative underground structures). An agency can contract with a comprehensive tunneling business or contract with prime consultants, tunnel lining engineers and designers, environmental specialists, and construction managers. There is business-to-business service like TMB rebuilding and design. A testament to this industry is an edirectory that carries listings for more than 125 tunneling businesses in the United States.

Tunnel Linings Service California might consist of:
•Tunnel liner and Portal Design
•Tunnel Rehabilitation
•Reinforced Concrete Lining Repairs
•Lining and Lining Finishes Evaluation
•Concrete Tunnel Linings – Fire protection
•Tunnel Lining Monitoring/Repair

California is the third largest state in the United States. It is a demanding terrain with a hindered water supply. The State of California is progressively “tunnelwise.” Tunnel Linings Service California.