Contractors' and Dealers' Association of California · San Francisco : L. A. Larson · leaf 871
h (he floor level as the workprogresses and materially aids in keeping the tunnel dry. The progress of (he excavadon through (his materialhas been at the rate of 9 feet per day, but as the driftsare in solid sandstone it is expected that the rate of prog-ress will be increased as less timbering… … Arch .Section Xear West Portal in Open Cut. The tunnel is excavated (o 12 or 18 inches below railgrade, and trenched along the sides for plumb posts andfor the concrete foofings of (he sidewalls. The muck hasbeen dumped into cars and hauled out by mules. At thewest end (he muck has been used (o…
Architecture · Building · Construction industry · Engineering
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