. The street railway review . iers as shown in the drawing, with bases designed todistribute 10 tons of combined load, carried by each post. Thenortherly abutment is a small aflfair of moulded concrete restingupon a shale ledge, and is little more than a retaining wall, since itcarries but one-half of the load of the north shore arms. The fiack wall is a height of 20 ft.; the wall is i ft. thick on top and liasa batter of I in. to the foot. The buttresses are 18 in. wide and 2ft. 8 in. deep. The back wall and buttresses rest upon a floor ofconcrete 18 in. thick, ij in. wide and 20 ft. long. Ih
. The street railway review . iers as shown in the drawing, with bases designed todistribute 10 tons of combined load, carried by each post. Thenortherly abutment is a small aflfair of moulded concrete restingupon a shale ledge, and is little more than a retaining wall, since itcarries but one-half of the load of the north shore arms. The fiack wall is a height of 20 ft.; the wall is i ft. thick on top and liasa batter of I in. to the foot. The buttresses are 18 in. wide and 2ft. 8 in. deep. The back wall and buttresses rest upon a floor ofconcrete 18 in. thick, ij in. wide and 20 ft. long. Ihe wing wall isreturned to meet the foundation wall of a building standing nearthe top of the bank. From the base of this abutment down the slope to the piers sup-porting the bent, and from thence to the southerly piers of thesouth tower and continuing in the center lire of the piers on eachside to the southerly piers of the northerly tower, is built a con-crete strut having a cross section of I -x 2 ft., in which is endiedded. VIEWS WALLS or GIILLV AND AliHTMl southerly abutment is somewhat more important, a^ it retains alarge amount of earth and carries one-half the load of ilie longersoutherly shore arms. It is necessarily of greater height and hasa much less secure footing in the uncertain soil which constitutesthe southerly slope of the valley. The nature of this southerlybank dclcrmined the character of the foundations, which as shownupon the plan consist of a lightly moulded concrete abutment withthe thinnest possible back wall, strengthened by the use of em-bedded rails and buttressed in front to carry the track ihc supporting floor course of concrete to the top of the a rail, as shown, the rail being 3 in. below the top of the last two piers to the north which receive the northerly ends ofthe concrete struts arc founded upon and against a ledge whichmade it necessary to go no further with the struts. Alternatingstrata of clay, shale,
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Keywords: ., book, bookcentury1800, bookdecade1890, booksubjectstreetrailroads
