Rialto Bridge

“ The Rialto is a graceful double bridge of white marble, which by a single span bridges the Grand Canal, leading from the bustling market-place to the opposite side, which is almost as busy. Like old London Bridge, it is crowded with little hucksters' shops; and I fancy there is little real change in the scene it presents from the time when the immortal [257] Shakespeare drew his Shylock and Antonio from life. The Hebrew is still a prominent figure in the thronged thoroughfare; but his victim, let us hope, is conspicuous by his absence. Humanity is somewhat softened since those days of yore. ”

“ The architects of the Renaissance showed great boldness in their designs. A granite arch built in 1377 over the Adda at Trezzo had a span at low water of 251 ft. This noble bridge was destroyed for military reasons by Carmagnola in 1416. The Rialto bridge at Venice, with a span of 91 ft., was built in 1588 by Antonio da Ponte. ”

“ The Merceria, a crowded thoroughfare, leads from under the Clock Tower in St Mark’s Square, after many kinks and turns, to the Rialto bridge over the Grand Canal, which is spanned by two other bridges about equidistant from the Rialto bridge. E. and W. of the Rialto, in addition to these bridges, numerous ferries (traghetti) make either bank of the Grand Canal easy of access, and small steamers (vaporetti) call at frequent piers the whole length of the chief waterway. Travelling by gondola, therefore, is to be regarded as a luxury rather than a necessity. ”

“ For many of them are of a great height, three or foure stories high, most being built with bricke, and some few with faire free stone. Besides, they are adorned with a great multitude of stately pillars made partly of white stone, and partly of Istrian marble.... There is only one bridge to go over the great channell, which is the same that leadeth from St. Marks to the Rialto, and joyneth together both the banks of the channell. This bridge is commonly called Ponte de Rialto, and is the fairest bridge by many degrees for one arch that ever I saw, read, or heard of. ”

“ Our first bridge is the Ponte di Paglia (or straw) , the wide and easy glistening bridge which spans the Rio del Palazzo at the Noah corner of the Doges' Palace. Next to the Rialto, this is the busiest bridge in the city. Beautiful in itself, it commands great beauty too, for on the north side you see the Bridge of Sighs and on the south the lagoon. On its lagoon façade is a relief of a primitive gondola and the Madonna and Child, but I have never seen a gondolier recognizing the existence of this symbol of celestial interest in his calling. ”

“ For the perfection of the whole, it was then proposed to construct the Bridge of the Rialto of stone, under the direction of the same master, with shops along its whole length. The entire work would, without doubt, have been a most admirable thing; but there were two causes wherefore these plans were never carried into execution: the first was that the republic, exhausted by the enormous expenses incurred in that war, was without money ”

“ It is a matter of notoriety that railroad bridges are built upon solid abutments of mason-work and resting on piers of stone between the abutments, thus giving strength and security to the frame above. It is not easy to see wherein such a structure differs from an ordinary bridge, except that, as it is to endure a greater burden, it is more solid and substantial. ”

“ Far too often their ideal of strength was a mere man-at-arms, brave but underbred. Rivers were obstructed by immense piers, for instance, by which spates were turned into dangerous inundations; and footways along bridges were so narrow that safety recesses for pedestrians had to be built out from the parapets into the piers. Even in exceptions to this rule of ungainliness, as in much Spanish workmanship, architects were overapt to make the use of bridges a tiring penance that wayfarers could not avoid. Thus the bridge over the Sella at Cángas de Onis has a lofty footway shaped like a gable ”

“ Tay Bridges and Titanics are like strong acts in a tragic play, whose influence we forget very soon. It is a thousand pities, for the next war may teach us, by frequent disasters, that machine-worship has been a mad gambler everywhere. Bridges suffered much from the priggishness of the Renaissance, but they have suffered infinitely more from the obsessions that ruined Sir Thomas Bouch. Poor Bouch! Not only did he wish to astonish the world by constructing an unparalleled bridge, wonderfully long, curved at both ends, and with a varying gradient. ”

“ Myself, I hate such a strumpet of a bridge as the Hoogesluis at Amsterdam, with her ornate spandrils, and her embossed masonry, and her balustraded parapet surmounted by a row of obelisks around which lamps are bracketed. Also I hate such a suspension bridge as the one at Conway Castle, where the metal rods that support the roadway pass through a brace of turrets on each of the embattled gateways. The effect is not only comic but ludicrous. No engineer with any sense would have put a metal viaduct within a few yards of Conway Castle. ”

“ On March 4, 1890, during a violent gale which blew from the south west with a pressure of 20 lb. per square foot, the Prince of Wales closed the last rivet in the north central girder, and from the south port of the south cantilever end pier declared the bridge open. ”

“ Thus the railroad crossing the Delaware at Trenton has, in this way, typified step by step every stage of the development of American bridge-building.
The timber bridges developed the steel truss bridge, the typically American construction, of to-day. In an earlier day the timber bridges were the glory of the engineer. Sometimes you see one of these old fellows remaining, like the long structure that Mr. Walcott built across the Connecticut River at Springfield, Mass., in 1805, and which still does good service; but the most of them have passed away. Fire has been their most persistent enemy. ”

“ The contractors have already completed the iron-work for the “first half” of the bridge; with the exception of this face-work, which will be finished somewhat later. It then only remains for the engineer to complete the road and pathway, and open the bridge for traffic. One obstruction will, we fear, remain. The blocks of houses on either side of the river (ultimately destined to be removed) , still look stable as ever—these abut directly upon the new portion of the structure, and will, if not removed before opening the bridge, make a sharp and inconvenient turn in the road necessary. ”

“ Some of these are carried over important rivers on stone piers, their roofing is decorative, and even to-day they would be useful in a time of unrest, especially to women and children. As for the Swiss variety of covered timber bridge, it seems to date from the period of lake-dwellings. But, whatever its lineage may have been, it is very ancient. Throughout the Middle Ages it was valued in war as well as in winter, when its footway was always free from snow. Often there was but a narrow space for light and air between the overhanging roof and the balustrade of heavy planks. ”

“ To avoid the possibility of any one claiming that draw-bridges should be constructed over all the mouths of the Pearl, large and small, crossed by the road in the vicinity of its junction with the Great Rigolet, it was provided that in the event the road passed below the principal entrance of Pearl river into the Great Rigolet, only one draw-bridge need be maintained in that locality, and that one over the Great Rigolet. ”

“ The celebrations of that day were the first public outburst of approval given to Eads's work. And to-day the strong and graceful bridge stands as his most beautiful and lasting monument. And as even the great tornado of 1896 was unable to do the piers any serious damage, they are likely to last indefinitely, and thus make the bridge "endure," as its builder said, "as long as it is useful to man." ”

“ As a rule, these road-bridges are simple and inexpensive in character, except in towns, or in cases where the line crosses the roads very obliquely, or where the road is situated at the top of a deep cutting, or bottom of a high embankment. Away from towns and out in the open country, permission is generally obtained to divert the roads to a moderate extent, so as to obtain a more favourable angle and height for the bridge; but in towns, where the roads become streets, sometimes of great width, with houses and shops on each side, little or no diversion can be allowed. ”

“ A cantilever bridge consists of two inverted trussed beams, each balanced on a pier, one part extending over the river and the other to the shore, where it is firmly anchored in solid, heavy masonry. The ends extending over the river toward each other from the opposite piers are joined by a short truss in such a manner as to permit expansion and contraction consequent on changes of temperature, and yet be proof against vertical or lateral pressure. Such a bridge, it is said, sustains scarcely any strain in the center of the span. Each half of the entire bridge is self-balanced on its pier ”

“ Hence each arch is complete and independent in itself, the piers having simply to sustain their vertical pressure. The arches are six in number, of 125 feet span each, the two approaches to the bridge being formed of cast-iron pillars and bearers in keeping with the arches.
The result is a bridge that for massive solidity may be pronounced unrivaled. It is one of the most magnificent and striking of the bridges to which railways have given birth, and has been worthily styled "the King of railway structures." ”

“ The supporting chains, which were brought from old Hungerford Bridge, are thrown over lofty turrets, resting in one case on a projecting bastion of rock, and in the other on a solid pier of masonry. These slender suspenders carry a roadway and two footpaths across a span of 700 feet. The bridge stands 245 feet above high-water level, and its altitude seems to furnish an irresistible temptation to people of a suicidal tendency. ”

“ The Americans have, however, outspanned all the rest of the world in their wire suspension bridges. They have thrown a suspension bridge of 800 ft. span over the Niagara at a height of 260 ft. above the water, to carry not only a roadway for ordinary traffic, but a railway. Suspension bridges are not well adapted for the latter purpose, but there seemed no other solution of the problem possible under the circumstances. ”

“ For all horse-drawn vehicles an increase of gradient on the bridges, beyond a certain limit, means, especially in wet or snowy or frosty weather, more slipping and falling, more stalling of all bridge traffic by such accidents, more wear and tear on horse flesh, and a resultant increased burden on the people. To raise the gradient of the bridges from those now existing to those indicated in the plans of the local United States Engineers' office would more than double the traction effort required in hauling over these bridges. ”

“ Their energy has evaporated in talk, like steam from a boiling pan. It was not until the bridge had fallen that the village hummed intelligently like a hive of bees, and set itself to work. What could be done then? Who was the landowner? No less a person than the Archbishop of Canterbury. Are we then to believe that in 1318 a Primate of England scamped his public duty? Was his attitude to a timber bridge inferior to that of the high priests of ancient Rome, who called themselves pontifices because they built and repaired the Pons Sublicius, a bridge of stakes at the foot of Mount Aventine? ”

“ The new high-level bridge, carrying the railway only, was opened by King Edward VII. in 1906; it consists of four steel spans on granite piers. The hydraulic swing bridge, on the low level, was built to replace a stone structure erected in 1781 on the site of a bridge dating from 1250, and destroyed by a flood in 1771. The Roman bridge, the Pons Aelii, is said to have spanned the river at the same point. The hydraulic bridge (1876) consists of one large centre pier, two midstream piers and two abutments; and its foundations are iron cylinders resting on the solid rock, 60 ft. ”

“ The piers are simple and excellent. Their width, twenty-six feet, is not too much for the spates of a freakish river, nor too heavy for the bridge as a linear composition; on the upstream side they have stern cutwaters, good foils in a piece of architecture that blends an alert grace with a supple vigour. Another point worth [Pg 317] noting is the gradient of a roadway that starts out from low abutments. Ammanati was bent upon being a friend to the traffic of Florence, and with the help of his cycloid arches he kept the road on a mild curve. ”

“ The breakwaters jut out too far, and meet the current with angles of even less than forty-five degrees; while the buttresses behind, on the down-stream side, are rectangular and almost without projection. Last of all, there is no ornament to dress the nude spandrils and to set them apart from the parapets. C’est là, en fait, une œuvre barbare....”
Let us conjecture, then, that this barbaric bridge at Albi, with its seven pointed arches, may belong, not to the time of Saint Bénézet, but to the year 1035, or thereabouts. ”

“ The short-span timber bridges were being displaced by concrete slab or concrete I-beam bridges. The reinforced concrete box culvert also became common. But aside from this, most of the growth consisted of further developments and refinements of existing bridge types. Riveted joints in steel trusses replaced the earlier pin connected joints, and stiffer and more substantial truss members developed. Steel rolled beam and built-up “plate girder” structures became common. The small arch brige changed from stone to concrete and began to grow in span length. Wider bridge roadways were being used. ”