Engineering Wonders of the World
Volume I

TRANSPORTER BRIDGES. 291 Fig. 6—NEWPORT TRANSPORTER BRIDGE. 592 FEET SPAN; HEIGHT ABOVE WATER, 177 FEET. car, the wire hauling ropes passing round a drum with spiral grooves. The centre of the car is used for wheel traffic, the two overhang- ing portions being covered for the use of pas- sengers, and divided into first and second classes. There is a staircase leading to the top of the towers, 280 feet high, whence a magnificent view of the surrounding country is obtained. The most important example of this type of bridge—with hinged tower legs and girder suspended from cables—is the one built at Newport, Monmouthshire, over Newport the river Usk, commenced in Bridge. 1903, the engineers being Mr. Robert H. Haynes and Mon- sieur F. Arnodin. The bridge is shown in elevation in Fig. 6. The span from centre to centre of towers is 645 feet, the clearance between the towers 592 feet, and the clear headway above high-water level 177 feet. The car, 33 feet long by 40 feet wide, is electri- cally driven by two motors of 35 horse-power each, actuating by continuous rope gearing the trolley running underneath the stiffening girder, from which is suspended the car. This trolley is 104 feet long, and is fitted with sixty steel wheels. The suspension cables are sixteen in number, four inside and four outside each of the stiffen- ing girders, and each contains 127 wires and weighs 4 tons. There is an equal number of anchor cables or backstays, which are not con- tinuous with the main suspension cables. As the backstays make a sharper angle at the top of the towers with the horizon than do the suspension cables, the stress on them is greater, and consequently they have a larger sectional area, that of the suspension cable being 3'9 square inches for each cable, against 4'27 square inches for the backstay. The weight of the suspension cables and backstays is 176 tons. The backstays are secured to large blocks of masonry for anchorage, each block containing 35,800 cubic feet of masonry. The two towers weigh 580 tons, the stiffening girders 560 tons. The foundation piers are placed in groups of four on each side of the river. They consist of masonry with steel shoes or kerbs, which