| 词条 | Mt. Lebanon Tunnel |
| 释义 |
|name = Mt. Lebanon Tunnel |image = Lebo tunnel_trolley_arriving_jeh.jpg |caption = South end |line = {{plainlist|{{Rail color box|system=PAAC|line=Red Line|type=Castle Shannon}}{{Rail color box|system=PAAC|line=Red Line|type=South Hills Village}}}} |location = Allegheny County, Pennsylvania |coordinates = |system = Pittsburgh Light Rail |status = operational |start = {{station link|PAAC|Dormont Junction}} |end = {{station link|PAAC|Mt. Lebanon}} |stations = 0 |startwork = |open = |close = |owner = Port Authority of Allegheny County |operator = Port Authority of Allegheny County |character = |construction= New Austrian Tunnelling method |length = {{convert|3000|ft|m}} |linelength = |tracklength = |notrack = 2 |gauge = {{RailGauge|5ft2.5in}} |el = overhead catenary |speed = |hielevation = |lowelevation= |height = |grade = }} The Mt. Lebanon Tunnel is a light rail tunnel in Allegheny County, Pennsylvania, also known as the Dormont/Mt. Lebanon Transit Tunnel, part of the Pittsburgh Light Rail system. The {{convert|3000|ft|m|adj=on}} long tunnel connects the {{station link|PAAC|Dormont Junction}} and {{station link|PAAC|Mt. Lebanon}} stations beneath Washington Road & West Liberty Ave. from Shady Drive East to McFarland Road at a maximum depth of {{convert|100|ft|m}}, and runs beneath a cemetery. The pre-tunnel trolley street line, which ended in 1984, ran from the long-removed Clearview Loop stop on Alfred St. (Mt. Lebanon) to the intersection of McFarland Rd. and Raleigh Ave. (Dormont). The tunnel was constructed by a technique called the New Austrian Tunnelling method, a tunneling process developed in the early 1960s that has become the primary tunneling practice in Europe. This is the first time that this money-saving technique was used for transit construction in the United States.[1] The difference with NATM lies in the means of support required to maintain the rock cavity and the configuration of the tunnel structure. With conventional tunneling, support of the rock cavity consists of a rib cage framework of steel beams and horizontal wooden planks. A reinforced steel concrete lining is added to create a perfectly shaped tunnel. With NATM, the rock surrounding the hole becomes the support system. This is done by lining the tunnel cavity with several thin layers of shotcrete, concrete that is blown on under air pressure.[2] The tunnel has continuous television surveillance.[3] References1. ^{{cite book |last1=Ozdemir |first1=Levent |title=North American tunneling: proceedings of the North American Conference Tunneling Conference 2004 |date= 17–22 April 2004 |publisher=CRC Press |isbn= 9789058096692 |page=473 }} 2. ^{{cite journal |date=April 1989 |title=Mt. Lebanon Tunnel: What Went Wrong |journal=Tunnels & Tunnelling |volume= 21|issue=4 |pages=61–62 }} 3. ^{{cite news |author= Joe Grata |title= Getting Around: In Pittsburgh's mini-subway, eyes are always watching |url= http://www.postgazette.com/pg/05191/535238-147.stm |work= Pittsburgh Post Gazette |date=10 July 2005 |accessdate=1 March 2009 }} External links
3 : Tunnels in Allegheny County, Pennsylvania|5 ft 2½ in gauge railways in the United States|Railroad tunnels in Pennsylvania |
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