File:Image from page 144 of "Official proceedings" (1901).jpg

English: Identifier: officialproceedi09rail

Title: Official proceedings Year: 1901 (1900s) Authors: Railway Club of Pittsburgh Subjects: Railway Club of Pittsburgh Railroads Publisher: Pittsburgh, Pa. : The Club Contributing Library: Carnegie Library of Pittsburgh Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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Text Appearing Before Image: iameter and 15 6 long, made of i steel plates stif-fened by five diaphragms dividing it into 12 cells. There were 24hydraulic jacks, each capable of 125 tons pressure, but the totalpower used did not exceed 1800 tons. Each lining ring is 18long, made up of 13 segments and a key. Each segmentweighs 1050 pounds and the total weight of the cast iron liningis 27000 tons. Parts of the Shield. It will be noted from the discussionthat the construction of the shield varies somewhat in accordancewith the character of the work under construction. The Bruneishield was rectangular in form to conform to the outline of histunnel section. jModern subaqueous tunnels are usually circularin order to get the benefit of the full strength of the circularform of section. This explains to some degree why the circularform is better adapted also to the shield. The system of tunnels under the North and East Rivers,by which the Pennsylvania Railroad gains access to New York Tunnels, rarticulaiiy v^ubaqueous. 95

Text Appearing After Image: ^^U< m o i a-^ o g r bi) to 96 Proceedings Railway Club of Pittsburgh.

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