. Electric railway gazette . FIG. 2.—ARCHED TOP READY FOR COVERING. The method of construction is very interesting ; itconsists broadly of excavating a huge trench, building aniron structure therein, filling in and regrading; the pass-age is too near the surface to resort to tunneling. Theiron structure is built of I-beams and plate girders, whichsupport brick and concrete arches. Under Charles Street,where the surface traffic is very heavy, beams are usedwhich are made up of angle iron and plates, but underthe public pleasure grounds, a 20-inch I-beam with a. FIG. 3.—VIEW OF THE INTERIOR. 7-i
. Electric railway gazette . FIG. 2.—ARCHED TOP READY FOR COVERING. The method of construction is very interesting ; itconsists broadly of excavating a huge trench, building aniron structure therein, filling in and regrading; the pass-age is too near the surface to resort to tunneling. Theiron structure is built of I-beams and plate girders, whichsupport brick and concrete arches. Under Charles Street,where the surface traffic is very heavy, beams are usedwhich are made up of angle iron and plates, but underthe public pleasure grounds, a 20-inch I-beam with a. FIG. 3.—VIEW OF THE INTERIOR. 7-inch flange is employed. The span is 24 feet and thespacing 3 feet. The section under the Common is a four-track passage, and therefore has a double span 48 feetwide with a line of supporting columns down the side columns are 15-inch I-beams with a rivetedplate foot, and the middle columns are built up of angleiron and plates. Each column rests upon a solid founda 412 ELECTRIC RAILWAY GAZETTE. Vol. XIII. No. 23. tion stone bedded in concrete. Fig. i gives a general viewof the iron work. When the iron construction work iscompleted, wooden formers are placed between the I-beams to facilitate the construction of the brick arches, asshown in Fig. 2, and when these are well formed theremaining space is filled up with concrete and leveled walls between the side columns are also arched toresist lateral pressure. Concrete only is used in the sidearches, except for the portions under Charles Street andthe Public Gardens, where the ground was
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1895
