. The Street railway journal . ut to allow for completely re-newing the air four times per hour, taking 1 800 cu. ft. of fresh airper person per hour as the requirement. It is believed the systemof having several comparatively small ventilating ducts connectingwith the outside air will give better results than would be securedby admitting the air through fewer large openings. The distribu-tion of the air between ventilating chambers will be accomplishedmainly by the plunger-like motion of the cars. If the circulationdue to the movement of cars and trains, accentuated by the s
. The Street railway journal . ut to allow for completely re-newing the air four times per hour, taking 1 800 cu. ft. of fresh airper person per hour as the requirement. It is believed the systemof having several comparatively small ventilating ducts connectingwith the outside air will give better results than would be securedby admitting the air through fewer large openings. The distribu-tion of the air between ventilating chambers will be accomplishedmainly by the plunger-like motion of the cars. If the circulationdue to the movement of cars and trains, accentuated by the stack at Twenty-Second Street, is not found sufficient,motor-driven fans will be placed in as many of the ventilationchambers as may be found necessary. SCHUYLKILL RIVER BRIDGEThe bridge upon which the subway tracks cross the SchuylkillRiver called for a design somewhat out of the ordinary, inasmuchas it was necessary to carry the two inner tracks on an ascendinggrade of about 4 per cent from the east to the west so as to bring. SECTION THROUGH SUBWAY VENTILATING DUCTS ALONGPENNSYLVANIA RAILROAD BUILDINGS the trains from the subway level on the east bank to the level ofthe elevated structure on the west bank; and to carry the two outertracks on a descending grade of per cent from the west riverpier to the ground surface at the west end of the bridge. Beginning at the easterly approach, the superstructure consistsof a plate girder approach span; a 98-ft. through Pratt truss; a214-ft. truss with curved lop, which is the main river span; a90-ft. Pratt truss, and an 82-ft. plate girder approach to the westshore. The cross sections of the bridge reproduced on PlateXLIX. show the gradual divergence of the inner tracks and outertracks at the centers of the respective spans. It will be noticed thatthe bridge structure begins at the eastern end just beyond the in-cline leading from the subway portal with the four tracks on thesame level, but reaches the west end as practically a dou
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectstreetr, bookyear1884
