International Correspondence Schools · Scranton, Pa. : The Colliery engineer co. · leaf 356
the tunnel. Thetunnel was driven from both ends, and when the headingsmet there was found to be less than a half inch discrepancyin the two lines. 1508. Tunnel Sections.—Tunnel sections varysomewhat, according to the material to be excavated, butthe general form and dimensions are much the same… … for single track from 14 to IG feet wide and from 17 to 20feet high. See Figs. 433 and 434. In seamy or rotten rock the section is sufficiently enlargedto receive a lining of substantial rubble or brick masonrylaid in good cement mortar. When the material has notsufBcient consistency to sustain…
Railroad engineering
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