The Viaduct Works' Handbook

26 The cost may be reckoned at €16 10s. per ton, delivered f. o. b. in England. A bridge of the same class was made at Crumlin, and erected over a part of the Thames, consisting of 3 spans, the centre one 88 feet 6 inches, and two side spans 85 feet 3 inches clear, three continuous girders 279 feet long, 7 feet 6 inches deep, the centre one 2 feet 6 inches wide, and side girders each 2 feet. Tons cwts. The weight of 2 side girders . . . . 81 13 „ 1 double girder . . . . 57 10 „ 56 cross girders . . . . 25 0 „ 4 longitudinal girders . . 28 8 Total . . . 192 11 This bridge was erected on cast-iron cylinder piers sunk deeply into the bed of the river, and filled in with masonry; the cost of the bridge, complete, was somewhat less than £40 per foot run. ARCHED GIRDER BRIDGES are sometimes used with economy, and they are selected for their more pleasing effect upon the eye than those of parallel girders. CURVED TOP PLATE GIRDER. BRIDGE Girders of the above form have been constructed at Crumlin, upon the designs of various engineers, and from these we select a bridge of 100 feet span for double line of railway carried on three girders, the centre girder being stronger than the side girders, and about 11 feet deep, 2 feet 6 inches wide on top, the floor composed of wood 8 inches thick, bolted to under side of girders; weight of Ironwork for 100 feet span, about 83 tons. » 90 „ 67 „ 80 „ 54 „ 70 „ 43 „ 2 60 „ 32 „ 2 50 „ 25 „