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单词 tunneled
释义 DictionarySeetunnel

Tunnel, Traffic

Tunnel, Traffic

 

a tunnel built at the intersection of heavily traveled urban traffic arteries to allow various types of vehicles to cross the intersection at different levels (see). Special structures or sections of roadway may be provided to allow pedestrians to cross traffic arteries (seePEDESTRIAN CROSSING). The placement of traffic tunnels is coordinated with the system of urban traffic circulation, the planning of streets and construction along them, and the installation of underground cables and sewers.

A traffic tunnel usually has a two-grade profile. As a rule, such a tunnel consists of one enclosed (tunnel) section and two open (ramp) sections that provide for the flow of traffic in two directions. Three lanes in each direction are customary in the USSR.

Traffic tunnels are constructed at a shallow depth and most often in open trenches. The enclosed section of a traffic tunnel is usually made of precast reinforced concrete in the form of a closed, two-bay frame. The open (ramp) sections consist of retaining walls, reinforced-concrete foundation blocks, and a drainage chute, which are combined into a single structural system by concreting the joints. Traffic tunnels are protected against water penetration by a waterproof lining. A reinforced-concrete framework is cast along the upper parts of the ramp walls and serves as a base for a parapet. Lampposts and the supports for trolley-bus power lines are usually installed on the parapet.

REFERENCES

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V. P. VOLKOV

tunneled


tunneled

(tŭn′ĕld) Placed surgically beneath the skin or into deeper tissues, e.g., into the intestinal wall. A tunneled catheter, e.g., is one that enters a vein through an incision made in the skin near the vein but then is passed through subcutaneous tissues to a second incision distant from the first. Tissue that surrounds the passage through which the catheter passes heals tightly around the catheter, holding it in place.

Unlike non-tunneled catheters, tunneled catheters can remain in place for many months. They are used for intravenous infusions, the administration of chemotherapy, hemodialysis, and blood drawing.

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更新时间:2024/12/23 12:34:59