Modern (18th-20th Century)

Sir Benjamin Baker: Born on 31 March 1840 in Keyford, now part of Frome, Somerset, England, United Kingdom. Deceased on 19 May 1907 in Pangbourne, England, United Kingdom.
Education: Apprentice at the ironworks Price & Fox, Neath Abbey (South Wales)
1862 - 1898.
Works in John Fowler's office; directs the construction of the London underground, 1867. Refitting work on three Telford Bridges: Menai Straits Bridge, Buildwas Bridge, and the Severn River Bridge near Gloucester; Cooperation on the Encyclopedia Britannica, 1882 - 1890.
Designs the Firth of Forth Bridge with John Fowler; Asswan Dam on the Nile

As a father and son, John and Washington Roebling were the foremost American engineers of suspension bridge construction in the nineteenth century. John Roebling was born in Muhlhausen, Thuringia in 1806. While in school he developed an interest in both metaphysics and in bridge building. He graduated with a degree in civil engineering from the Royal Polytechnic Institute of Berlin in 1826.

In 1831 Roebling and his brother immigrated to Pennsylvania to farm. When this venture failed, Roebling accepted the position of Pennsylvania state engineer. In this position, he surveyed and supervised the construction of canals, locks, and dams.

In 1841 Roebling invented the twisted wire-rope cable, an invention which foreshadowed the use of wire cable supports for the decks of suspension bridges. Six years later he established a factory in New Jersey for the manufacture of this cable. Because the cable could support long spans and extremely heavy loads, Roebling quickly gained a reputation as a quality bridge engineer.

Upper Delaware Scenic and Recreational River is the home of the oldest existing wire suspension bridge in the United States — the Delaware Aqueduct, or Roebling Bridge as it is now known. Begun in 1847 as one of four suspension aqueducts on the Delaware and Hudson Canal, it was designed by and built under the supervision of John A. Roebling, future engineer of the Brooklyn Bridge.

Portions of the D & H Canal, including the Delaware Aqueduct, were designated a National Historic Landmark in 1968. The Delaware Aqueduct is also designated a National Civil Engineering Landmark.

...A German immigrant, and graduate of the Royal Polytechnic School of Berlin, Roebling came to the United States in 1831. It was not until 1845 that he built his first suspension structure. From 1845 until his death in 1869, he designed five major suspension bridges. Two — the Cincinnati-Covington Bridge and the Brooklyn Bridge — are still standing.

The first iron bridge was constructed in 1779 at Coalbrookdale, a cast-iron arch. Cast iron then began to replace stone, quite successfully in arch bridges, but the attempt to use cast-iron beams ended in the failure of Robert Stephenson's Dee Bridge. Thereafter, cast iron was used for compressive members only, and engineers turned to wrought iron as a tougher, more reliable material, using it first in massive tubular girders riveted together from the small plates which were all that were available at the time. Wrought-iron link chains were used for suspension bridges by Telford and Brunel.

In the United States, iron was expensive and largely imported from Britian because of the primitive state of the domestic iron industry. Wood, however, was abundant and cheap, and it was good hardwood that made an excellent material of construction. Wood, therefore, was the material most often used for even major bridges, with spans greater than 50 feet. We are not talking here of the trestles and king-post trusses used for minor bridges, but bridges that crossed the rivers and gorges that abounded. Two kinds of bridges were in common use, the lattice truss and the trussed arch, of which there were as many varieties as there were builders. Bridge builders were self-taught craftsmen and amateurs, for the most part.

The Berlin Iron Bridge Company was Connecticut's only large-scale fabricator of metal-truss bridges in the 19th century. Some 400 employees worked at its East Berlin plant, and hundreds of others worked in the field erecting the bridges. Over 1,000 Berlin bridges are believed to have been built before 1900. Most were in the Northeast, but even today Berlin bridges survive as far away as Texas. The company mostly built small-town highway bridges using its patented lenticular or parabolic truss. However, the Berlin Iron Bridge Company was prepared to take on any kind of fabrication work, including multiple-span city bridges, suspension bridges, drawbridges, and railroad bridges.

Hundreds of Berlin bridges were built in the company's home state of Connecticut. As of this date (August, 2001) only 13 highway bridges, 2 railroad bridges, and 2 millyard bridges are known to have survived.

The bridge maker’s signs advertised the builders of the wrought iron bridges that were popular at the turn of the century. These were collected in Central Illinois during 1968-70. There are over 180 signs represented under the “Maker’s Sign” icon. The bridge signs and the bridges they represent are under the major category icon “Iron Bridges”.

Addressing the shortcomings of the Burr truss, namely its expense and specialized labor, Ithiel Town patented his lattice truss design in 1820. The lattice design fastened simple, diagonally set planks with treenails, or wooden pins, into crisscrossing truss system secured by top and bottom chords. Thus, Town's truss eliminated the need for large and expensive timbers, used in the Burr truss' series of arches, and streamlined the intricate, time-intensive labor of fastenig mortice-and-tenon joints into the simple slotting and wedging of treenails. Town's innovative truss design is visible today in two of Connecticut's three remaining covered bridges, Bull's Bridge in Kent and West Cornwall Bridge in Cornwall and Sharon.

When the retreating French Army and its allies reached the banks of the ice-filled Berezina River on the 23rd of November, 1812, they discovered their sole means of escape blocked by the smoldering ruins of the Borisov bridge. On the opposite bank lay a Russian force under Admiral Pavel Vasil'evich Chichagov, sent there specifically to cut off the French retreat from Russia. But with ingenuity born of desperation, French Engineer Jean-Baptiste Éblé and four hundred pontonniers managed to quietly build two new bridges using materials taken from nearby houses. Only days before this the French Army's Commander-in-Chief, Napoleon Bonaparte, had ordered all sixty boats of the army bridging train to be burned along with all other "nonessential" gear. General Éblé protested the decision at the time and discretely ordered two wagons of charcoal and six wagons of tools to be spared. He also assigned each of his men to carry a tool and some cramp irons. The Berezina bridges would be built using only these hand-tools, during the winter, for an army on the verge of disintegration.

Consists of the author's A work on bridge-building : consisting of two essays, the one elementary and general, the other giving original plans and practical details for iron and wooden bridges. Utica, N.Y. : H.H. Curtis, 1847, plus supplementary text, Notes in correction and explanation of the original text, and Central forces.

The first covered bridge in America crossed the Schuylkill at High Street, now Market Street -- a familiar enough spot to generations of Drexel and Penn students and faculty! It replaced a pontoon bridge, and for that reason it was called The Permanent Bridge. It was not originally planned as a wooden or covered bridge, but rather as a stone bridge. The abutments and piers had been begun in 1800 and were complete in 1804, when the decision was made to complete the Permanent Bridge as a wooden bridge. For this purpose, Thomas Palmer, a bridge architect, was brought from New England. Palmer's bridge was braced with three arches and multiple kingposts. The suggestion that it be covered came from Judge Richard Peters, president of the Permanent Bridge Company. Palmer supported it, expecting the bridge to last thirty, and perhaps even forty years, if covered. Owen Biddle, a Philadelphia architect and builder, did the woodwork and ornamentation that were to make the bridge a memorable Philadelphia landmark.