最終更新日:2022/12/24

The track blanketing required excavation of up and down main lines to a depth of 4½ft below rail level for 1⅜ miles, to allow the defective track bed to be removed and replaced by a new formation. … a layer of polythene was employed by the E.R. at the base of the new formation; … On top of the polythene is laid the sand, as a blanketing and drainage medium, and above that the ballast.

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