The roadway of the bridge is divided into five thoroughfares. Those on the outer sides are for vehicles, and are 19 feet wide; the centre is for foot passengers, and is 15½ feet in width; while the two others are for tramway traffic. The bridge was opened in 1883, and affords a great triumph of engineering skill.
Much smaller, but none the less interesting, is the Suspension Bridge at Clifton. As far back as 1753, Alderman William Vick, of Bristol, left a sum of £1000 to build a bridge at Clifton. The sum was to lie at compound interest until £10,000 was reached. However, the money was increased by subscriptions, and in 1830 an Act of Parliament was obtained for its construction.
The work coming into the hands of Mr. I. K. Brunel, he designed a bridge of 702 feet span, and 250 feet above high-water. The piers and abutments were built, but lack of cash, which forms an obstacle to so many brilliant enterprises, stopped the progress of the bridge for nearly fourteen years.
Then it occurred that the Hungerford Suspension Bridge was to be removed to make way for the Charing Cross Railway Bridge, so the chains were purchased at a comparatively small cost, and the work at Clifton proceeded, and was finally completed.
Three chains on either side suspend long wrought-iron girders, which help to stiffen the platform; and cross girders between support the floor. The chains pass over rollers on the piers, and are ultimately anchored to plates bedded in brickwork abutting on rock. The platform is hung by upright rods from the chains, and hand-railing is used with lattice-work, to assist in rendering it rigid. The roadway, twenty feet wide, is made of creosoted wood, five inches thick, while the pathways on either side are made with wood half as thick. Between the piers the weight of the structure, including the chains, amounts to nearly a thousand tons.
In all these suspension bridges, however large, the principles are much the same. The platform, or roadway, is hung from chains or cables, which pass over piers and are anchored fast at the ends. Some are stiffened with girders and bracing to prevent undue undulation. The chains take a graceful and definite curve, that of the Menai Bridge dipping fifty-seven feet. The strain is the greatest at the lower part, and is increased, should the chain be drawn flatter over the same space. These bridges became widely adopted.
But there came a time when none of the bridges in vogue seemed to give what was required. A new principle was wanted. Where was it to be found?
CHAPTER IV.
THE GREATEST BRIDGE IN THE WORLD.
“Have you heard the news? The Tay Bridge is blown down!”