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Blucher, Stephenson's first locomotive, site of
West Moor, Killingworth, Tyne & Wear, UK
associated engineer
George Stephenson
date  1814
era  Georgian  |  category  Steam Engine or Locomotive  |  reference  NZ278712
The Great East River Bridge, later called Brooklyn Bridge, crosses a treacherous waterway many believed unbridgeable. The project was a Roebling family enterprise — John, its designer, died before construction began and his work was carried on by son Washington and daughter-in-law Emily, a worthy role model for women in engineering. The hybrid suspension bridge they built was then the longest in the world and remains in constant use. It was the first bridge in America to use steel wire cables.
In the winter of 1852, German-born John Augustus Roebling (1806-69), an engineer and manufacturer of twisted wire cable, and his son Washington Augustus Roebling (1837-1926) were trapped on a ferry on the deep, turbulant, and frozen East River — “one of the busiest stretches of navigable saltwater anywhere on earth”. Roebling senior conceived the idea of constructing a suspension bridge, connecting Manhattan with Brooklyn and enabling commuters to cross whatever the weather.
Suspension bridges previously designed by Roebling include Smithfield Street Bridge (Pittsburgh, opened 1846, replaced 1883) and Roebling's Delaware Aqueduct (Pennsylvania, 1849). Brooklyn Bridge would be not only the longest in America but the longest in the world too.
On 19th June 1857, Roebling wrote to iron manufacturer Abram Stevens Hewitt (1822-1903), iron wire supplier, to suggest the new bridge. Hewitt subsequently printed the letter in New York's Journal of Commerce, where it "attracted great attention". Meanwhile, in 1857, Washington Roebling graduated in engineering from Rensselaer Polytechnic Institute in New York and began assisting his father on bridge projects. In 1861, he enlisted in the Union Army and fought at Gettysburg during the American Civil War (1861-5). In 1865, he married Emily Warren (1843-1903).
However, Roebling senior's idea for a bridge over the East River remained just an idea until the winter of 1866, when the river froze for weeks and the ferries could not operate. By this time, he had completed Niagara Falls Suspension Bridge (1854), Allegheny Bridge (1859, dem. 1892) and Cincinnati-Covington Bridge (1866).
Brooklyn businessman and contractor William Charles Kingsley (born Kinsella, 1833-85) and state senator Henry Cruse Murphy (1810-82) championed Roebling's scheme. Murphy drafted the legislature bill and civil engineer Julius Walker Adams (1812-99) provided a cost estimate of $5m. The sum was low enough to secure approval from Congress in spring 1869, along with sufficient investment to start the project.
In April 1867, the New York Bridge Company was formed. It was allowed to levy tolls on pedestrians and vehicles, for an annual profit of not more than 15 percent. Kingsley became a major shareholder, and company president in 1882, succeeding Murphy. Thanks to the influence of corrupt New York politician William Magear 'Boss' Tweed (1823-78), Kingsley received a commission of 15 percent of the construction costs until 1873, and $10,000 per year thereafter until the bridge opened.
On 23rd May, John Roebling was appointed chief engineer for the bridge. His design, presented to the company on 1st September 1867, was on an unprecedented scale — taller than any other structure on the New York skyline at the time. He pronounced proudly, that it would be "not only be the greatest bridge in existence, but it will be the greatest engineering work of the continent and of the age”. He also predicted the need for additional bridges over the East River as the New York and Brooklyn grew.
Roebling’s original estimate for the bridge was $7m. However, the US government asked for the main span to be raised to provide 1.5m more headroom for shipping. The deck was also to be widened from 24.4m to 25.9m. The estimate increased, first by 8 percent and then more when the cost of the tower foundations was recalculated.
The design is for a bridge 1.83km long including the approaches, and 1.05km between stone anchorages. The side spans measure 283.4m, with the main span 486.3m long, arching above mean high water by 36.3m at the towers and 40.5m at midspan. The deck is suspended by four cables — for the first time entirely of steel — between two limestone and granite towers, rising to 84.3m above the river. Roebling planned to use caissons in the construction of the submerged tower bases, so Washington and Emily spent a year in Europe investigating the technology.
In June 1869, New York City Council and the US Army Corps of Engineers approved the design. On 28th June, Roebling was surveying positions for the Brooklyn (south east) tower. A ferry crashed into the slipway where he was standing and crushed his foot. His injured toes were amputated. Roebling refused anaesthetic and following surgery treated the wound himself, but he developed tetanus and died on 22nd July.
In August 1869, Washington Roebling, who was now 32 years old, was apponted in his father's place. His loyal band of assistant engineers comprised Charles Cyril Martin (1831-1903, principal assistant) and Francis Collingwood (1834-1911), both graduates of Rensselaer Polytechnic Institute, Wilhelm Hildenbrand (1843-1908) who had worked with John Roebling, William H. Paine (1828-89), Samuel Risler Probasco (1833-1910) and George W. McNulty (c1850-1924).
Emily Roebling was an unacknowledged member of the team. She had studied algebra, geometry, astronomy, chemistry and geology at the Georgetown Visitation Convent in Washington DC — and she was an expert horsewoman. Her interest in the bridge project led her to learn about strength of materials, stress analysis, cable construction, calculation of catenary curves and more.
On 3rd January 1870, work commenced on site. In March, the Brooklyn caisson was launched, towed into place and sunk in early May, becoming operational on 21st May. The caisson was made of coursed Southern pitch pine timber in the form of huge upturned box, effectively a diving bell. It had two air locks, two supply shafts and two water shafts, where clamshell scoops collected the arisings. Once in position, compressed air was fed in, driving out the water. More than 100 men could dig inside box.
The Brooklyn caisson was 51.2m long, 31.1m wide and 6.6m high, with a massive roof 3.7m thick. Its tapering walls were 2.7m thick at the top and only 200mm thick at the base. The timber courses were through-bolted and the narrow base edge shod with iron. All joints were filled with pitch. As the river sediment was excavated (by hand) and removed, the narrow toes of the walls enabled the caisson to move downwards under the weight of the towers being constructed above.
On 10th July 1870, the Brooklyn caisson broke ground on the riverbed. Work continued around the clock, three shifts a day, six days a week. Progress was slow. Initially the caisson descended by less than 150mm a week, until Washington used dynamite to break up larger boulders, increasing the rate to 450mm a week.
It was a hot, damp, noisy and dangerous workplace, lit by calcium lights. A blowout (compressed air escaping suddenly) could depressurise the box and risk the river breaking in. Once, Washington was in the caisson when a supply shaft door burst. The project’s master mechanic described working under pneumatic pressure as causing an effort to speak, an erratic pulse rate and a sensation in the head like "the rush of many waters". A few workers suffered from decompression sickness, or 'the bends', about which little was known at the time. [Dissolved nitrogen in the bloodstream forms bubbles when a person returns too rapidly to atmospheric pressure. These block oxygen supply, resulting in acute limb pain and potentially fatal effects on the spinal cord or brain.]
On 1st December 1870, the timber roof of the caisson caught fire, presumably caused by the gas lamps in use inside. The roof was supporting more than 25,000 tonnes of partly constructed tower and its failure would have been catastrophic. The caisson had to be flooded to extinguish the blaze but was found to be structurally sound when pumped out days later. Washington, who had been in the caisson and stayed on site until the fire was out, developed some paralysis in his limbs as a result of the bends.
The Brooklyn caisson eventually reached bedrock, 13.6m below the waterline. The void inside the timber box was then filled with concrete to form a permanent foundation, which was completed on 11th March 1871.
In May, the New York caisson was launched. It was 1.2m longer than its pair, and 9.6m high, with a thicker roof. To guard against fire, the interior was lined with airtight iron plating. With bedrock predicated to be some 10m deeper than on the Brooklyn side, requiring higher air pressure to keep water out of the workings, Washington worried about more cases of the mysterious illness.
On 12th December, caisson sinking commenced. As it reached 15m below water, the first workers succumbed to the bends. At 18m, more workers were afflicted, and some suffered paralysis. By the time it was 21m deep, men were dying. The maximum pressure in the base of the Brooklyn caisson was 145kN per sq m (21 psig), but in the New York caisson it went up to 255kN per sq m (37 psig). Collingwood ruled that, compared with working a shift in normal atmospheric pressure, a man labouring under two atmospheres of pressure should work for about half the shift time, under three atmospheres one-third of the time and under four atmospheres one-quarter of the time.
Dr Andrew Heermance Smith (1837-1910), surgeon to the bridge company, was in charge of medical care. He built baths and an infirmary on site and spent time inside the caisson to investigate the illness, publishing a paper in 1873 — The Effects of High Atmospheric Pressure Including the Caisson Disease. Between 25th January 1872 and 31st May 1873, he treated 110 cases — three men died. It’s likely there were many more unreported or less serious cases.
Smith noted serious effects resulted from pressure of 165kN per sq m (24 psig) or more. He advised against workers enduring rapid changes of pressure. He also recommended constructing an airtight iron tube in which a sufferer could gradually ‘decompress’. However, the suggestion was not adopted.
In May 1872, at a depth of 23.9m below water level, the caisson grounded on a layer of compacted sand and gravel. Washington Roebling decided leave the caisson at this level rather than risk further injuries. In July, the New York caisson was filled with concrete.
Around this time, Roebling suffered a far worse attack of the bends. He collapsed, paralysed. Though he survived he was plagued with fatigue, depression, irritability, stomach problems, constant pain and loss of feeling in his legs. He was unable to leave his room in New Jersey, almost 100km from New York, but continued to work, even though his eyesight was affected.
He was nursed by his wife — the only person he allowed to help him. Emily Roebling became his partner on all bridge matters, dealing with correspondence, taking notes of plans and instructions and relaying them to the assistant engineers. She visited the site frequently, negotiating materials supplies and overseeing contracts.
Nevertheless, the New York Bridge Company was growing nervous. Emily met with Murphy, the company president, in New York and persuaded him to agree to keep the chief engineer in post, on condition that bridge construction proceeded as scheduled. Her tact in dealing with all parties concerned, and her evident knowledge of engineering, led many to believe that she was the key decision-maker and far more than a surrogate for Roebling.
By December 1872, the Brooklyn tower was 42m above the river and the New York tower was taking shape. Granite and limestone blocks for the towers were towed on barges and raised to the top of the towers using timber derrick cranes.
In 1873, the Roeblings spent six months at a spa in Wiesbaden, Germany. However, the treatment brought no improvement and they returned to New Jersey. Washington Roebling never returned to the bridge site.
At this point, work on the two anchorages was underway, with housing and warehouses demolished to make space for the massive structures. The anchorages are of limestone masonry, set back 283.5m from each tower and rising 27.4m above high water level. Each measures 36.3m x 39.3 at the base and 31.7m x 35.7m at the top, and weighs about 54,430 tonnes.
Within each anchorage are embedded four cast iron anchor plates, one per cable, connected to four anchor chains that follow a rising arc through the masonry to hold the ends of the cables. The anchor plates are oval, 5m by 5.3m and 6.4m thick in the centre, and weigh some 21 tonnes apiece.
The Brooklyn anchorage was constructed from February 1873 to November 1875, the New York one between May 1875 and July 1876 — the latter bears a bronze plaque commemorating the land below it as the site of America’s first presidential mansion (dem. 1856). George Washington (1732-99) lived here during his first ten months as the first president.
The Brooklyn tower was completed in May 1875 and the New York tower in July 1876. Each has two openings with pointed Gothic arches, 10.3m wide and 36.7m high, commencing 36m above high water. Above the arches, the towers rise another 9.1m, where iron bedding plates support segmental cast iron saddles for the suspension cables. Roller bearings between the plates and the saddles prevent the cables slipping or chafing.
With the towers and anchorages finished, work began on adding the cables. On 14th August 1876, a scow transported a coil of wire rope to the Brooklyn tower, one end was hoisted over the top and pulled down to the anchorage. The boat then moved to the other tower, paying out the wire, which was then hoisted over the tower and connected to a winding engine, which dragged it out of the water. The end was then fixed to the other anchorage. A second wire was installed and joined to the first, forming an endless rope traveller, powered by a steam engine.
On 25th August 1876, Farrington made the first crossing, seated in a 'boatswain’s chair' (swing). The journey took 22 minutes.
In 1877, the Roeblings relocated to their house in Brooklyn. When officials, engineers or contractors visited to discuss the bridge, it was usually Emily who resolved their concerns. Early that year, a narrow footbridge of timber planks was built as access for the bridge workers. It spanned the river in a catenary curve over the towers, with two wires acting as handrails. A notice at the start warned, "Safe for only 25 men at one time. Do not walk close together, nor run, jump or trot. Break step!"
In June 1877, cable spinning commenced. To explain the technique to the multi-lingual workforce, a scale model was made of the machinery, wire ropes and temporary footbridge. Workers (and presumably winding engines) on strategically placed platforms passed a continuous steel wire over one tower, across the river, over the second tower, through the anchorage and back again, repeating as many times as it took to form a strand.
Originally, each of the four suspension cables contained 19 strands of 278 wires (5,282 wires in total) about 3mm in diameter. Each strand is one continuous skein of wire, spun back and forth between the anchorages 278 times.
However, in November 1877, one of the wires snapped. A sample was sent to Roebling who described it as "brittle as glass". It had not been made by John Roebling's Sons Company but supplied by contractor J. Lloyd Haigh. As the inferior wire could not be taken out of the cables, 152 extra good quality wires were installed in each cable at Haigh’s expense. Fortunately, Roebling had allowed a big safety margin in his cable design and calculated that even with the low grade wire, the cables could carry some five times the anticipated load.
In June 1878, one of the cable strands broke loose from the New York anchorage, taking the anchor plate with it, and plunged into the river. It injured several of the bridge workers, two of them fatally, and just missed the crowded Fulton Ferry.
Despite such setbacks, in October 1878, the last wire was spun across the bridge. Clamp tongs were used to compress the strands into a cylindrical cable, 400mm in diameter and 1.09km long, which was bound with wire at 380mm intervals along its length. Each of the four suspension cables consists of 5,434 steel wires (19 strands of 286 wires) and weighs 786 tonnes.
Bridge deck construction now commenced. The deck is of longitudinal and transverse steel truss girders with diagonal bracing. It is carried on six principal longitudinal ribs that pass through the tower openings, resting on the masonry underneath and anchored to it by bolts and wire rope ties.
Transverse beams on top of the ribs support the carriageways. The principal crossbeams are 838mm deep trusses, 2.3m apart, to which are attached the steel hangers from the cables (four hangers, one from each cable). The hangers are either steel wires or steel rods. Lighter crossbeams and short longitudinal beams are fixed halfway between the principal transverse beams, to give the decking additional support.
As additional stability — relieving some of the cable loading and preventing vertical oscillation of the deck — stay cables fan out from the tops of the towers. The bridge is thus a hybrid of suspension and cable stayed technology. The wire rope stays meet the deck at 4.6m intervals, over a distance of 121.9m from the towers.
To protect against buckling under wind loading, the deck has a curving network of horizontal wind braces beneath it, braced more heavily near the towers. Construction of this under-structure of stiffening trusses, and the carriageway, began in March 1879 and continued into 1883.
Originally, the deck carried one rail track and two (horse-drawn) vehicle lanes 5.8m wide in each direction, with a 4.7m wide walkway for pedestrians and cyclists, 3.65m above the centreline of the deck. The outer parapets to the deck, also steel trusses, are 2.4m high.
Terminal buildings of iron were constructed at both ends of the bridge, to collect tolls, and 70 electric lamps installed along the walkway. The 'cars’ or trains on the rail tracks were hauled between the termini by a stationary engine working an endless rope.
As with everything about the bridge, its approaches are on a grand scale. The New York approach is 476m long and the Brooklyn approach, on higher land, is 296m. The voids under the road viaduct arches were used as warehouses.
During 1879, Farrington gave several well received public lectures about the bridge’s construction — one of them attracted an audience of more than 2,000 people. However, many believed the lectures were actually written by Emily Roebling. In 1883, she would be the first woman to ever address the American Society of Civil Engineers.
In 1881, a delegation of bridge company trustees visited the site. They climbed to deck level at the Brooklyn tower, where they were met by Emily. She led them over the suspended walkway while describing the construction, seemingly unconcerned about its height above the river. Some of the trustees made the return journey on the ferry!
In 1882, she needed all her diplomatic skills to deter Seth Low (1850-1916, mayor of Brooklyn 1882-5) and some of the other trustees from removing her husband from the project. Low apparently had not met Roebling but still denounced him, saying, "at every point there is a weakness in the management of the Brooklyn Bridge. The engineering part of the structure — the most important — is in the hands of a sick man". The blame for cost increases and delays was later attributed to Murphy, Kingsley and fellow trustee James Samuel Thomas Stranahan (1808-98). The motion to depose Roebling was defeated by the board of trustees with a 10 to seven majority vote.
Also in 1882, disharmony between Martin and Farrington resulted in the master mechanic leaving the project. Martin, formerly principal assistant engineer, was the bridge’s chief engineer between 1883 and 1902.
In April 1883, the bridge was completed and Emily Roebling the first person to drive across it, in a grasshopper gig with retractable hood. The bridge cost some $15.5m to construct, including land purchases of $3.8m. It weighs 13,317 tonnes in total (suspended main span structure 6,006 tonnes), the towers contain 65,109 cu m of masonry and the wire strands cover 22,627km. Altogether 27 workers lost their lives during its construction. The labour rate paid to the workforce, averaged over all trades, was $2.50 per day.
On 24th May 1883, Brooklyn Bridge opened to the public. Around 150,000 people crossed on the first day. An enormous crowd gathered for the opening ceremony, conducted in front of 6,000 invited guests. Chester Alan Arthur (1829-86), the 21st president, New York Governor Stephen Grover Cleveland (1837-1908), Congressman Henry Warner Slocum (1827-94) and New York mayor Franklin Edson (1832-1904) arrived at the Manhattan end of the bridge to be greeted by Kingsley. Washington Roebling was absent.
The party progressed to the Brooklyn end of the bridge to join Low for three hours of speeches. Only one speaker, Congressman Hewitt, recognised Emily's role in an extraordinary engineering achievement. He declared, "One name ... cannot be passed over here in silence ... It is thus an everlasting monument to the self-sacrificing devotion of woman, and of her capacity for that higher education from which she has been too long disbarred. The name of Mrs. Emily Warren Roebling will thus be inseparably associated with all that is admirable in human nature, and with all that is wonderful in the constructive world of art."
On 30th May, known then as Decoration Day (forerunner of Memorial Day), the bridge was crowded. Panic broke out near the New York end and caused a stampede in which 12 people were trampled to death and many more were injured.
In September 1883, the cable-hauled train cars began running. By 1888, they were carrying more than 30m passengers a year. In May 1884, showman Phineas Taylor Barnum (1810-91) marched 21 elephants across the bridge in to demonstrate its robustness. On 19th May 1885, swimming instructor Robert Emmet Odlum (1851-85) was the first person to jump from the bridge but unfortunately did not survive.
In 1898, Emily wrote candidly to her only child John Augustus Roebling II (1867-1952), confirming what some people had long suspected, “… I have more brains, common sense, and know-how generally than any two engineers civil or uncivil that I have ever met, and but for me the Brooklyn Bridge would never have had the name of Roebling in any way connected with it! It would have been Kingsley's Bridge if it had ever been built! Your father was for years dead to all interest in that work.”
In the same year, the bridge deck was reconfigured to allow trolleys and motor vehicles to travel in the outer lanes. The train cars on the inner lanes were later replaced by elevated subway trains.
In 1903, the Brooklyn Bridge ceased to be the longest suspension bridge in the world. Its successor was the nearby 2.2km long Williamsburg Bridge, with a main span just 1.4m longer. By 1910, the toll on Brooklyn Bridge was removed after the City of New York passed a law prohibiting the use of tolls to finance the construction and maintenance of its bridges.
Emily Roebling died in 1903 and Washington Roebling in 1926. They are buried in Cold Spring Cemetery, Cold Spring, Putnam County, New York.
In 1944, the elevated subway trains were discontinued and the terminal buildings dismantled. The trolley lines ended their services soon afterwards.
Between 1944 and 1954, noted bridge engineer David Barnard Steinman (1886-1960) supervised a comprehensive but unobtrusive refurbishment project. The bridge’s inner and outer deck trusses were strengthened, new horizontal stays installed between the suspension cables, and the rail and trolley tracks removed. The outer edges of the deck were widened to increase the roadways from two lanes to three in each direction, the deck surfacing replaced by a 75mm thick concrete filled steel grid and new approach viaducts constructed. The project cost $9 million.
In 1951, a tablet was erected on the bridge by The Brooklyn Engineers Club, funded by popular subscription. Its inscription reads, “The builders of the bridge dedicated to Emily Warren Roebling (1843-1903) whose faith and courage helped her stricken husband Col. Washington A. Roebling, C.E. (1837-1926) complete the construction of this bridge from the plans of his father John A. Roebling, C.E. (1806-1869) who gave his life to the bridge. ‘Back of every great work we can find the self-sacrificing devotion of a woman’.”
The bridge is designated a National Historic Landmark (29th January 1954), and listed as a National Monument by the National Park Service (2nd July 1964) and the New York City Landmark Preservation Commission (24th August 1967). In 1967, a large collection of Washington Roebling’s original sketches for the bridge were discovered in a Brooklyn carpentry shop at 352 Kent Avenue, under the Williamsburg Bridge.
Additional approach ramps to between the north west end of the bridge and FDR Drive were constructed later and opened to traffic in 1969.
In 1979, the New York City Department of Transportation instigated an in-depth inspection of the bridge, to determine the renovation priorities over the next 100 years. During 1981, two of the bridge’s 216m stay cables snapped, but the bridge did not collapse, thanks to the Roeblings’ foresight.
On 24th May 1983, the centenary of the bridge’s opening of the Brooklyn Bridge was celebrated with parades, a flotilla of tall ships and a firework display. President Ronald Reagan (1911-2004) led a procession of vehicles across the bridge.
In 1986, an extensive bridge rehabilitation project was launched. Computer modelling was undertaken, using 3D finite element programming. Between 1986 and 1991, all the broken and damaged vertical hangers, cable posts, stay cables, suspension cable wrapping and horizontal cable ties were replaced and all the hangers adjusted. Traffic flows remained live throughout the work, though temporary lane closures were allowed outside busy commuter periods.
Around 1995, a team of consulting engineers examined the remaining capacity of the Brooklyn Bridge approaches, using impact echo and flat jack testing. The techniques allowed a more accurate assessment of the condition of the brick soffits of the arches, which are covered with sprayed concrete, and the in-situ compressive strength and modulus of the brickwork.
In February 1999, bridge inspectors discovered the surfacing concrete was spalling and breaking away from its steel grid, weakening the bridge deck. An emergency redecking project was carried out, completed in October. The deck surface was replaced by precast steel and concrete panels costing $33.5 million.
Also in 1999, the Manhattan bridge approach over Franklin Square was refurbished. The existing trapezoidal deck trusses were retrofitted with six steel arches, anchored into the original masonry abutments. The arches vary in length from 44.8m to 57.9m to fit the original framework.
In March 2006, during a regular bridge inspection, a secret chamber was discovered inside one of the masonry arches of the Manhattan approach. Its exact location was undisclosed, for security reasons, because the chamber was to be used as a fallout shelter in the event of a nuclear attack. It contained more than 350,000 items, dated 1957 and 1962, including water drums, food canisters, medical supplies and blankets.
In 2009, the New York City Department of Transportation analysed the city’s bridges to evaluate whether they met current seismic guidelines. The results showed the Brooklyn Bridge’s foundations are capable of withstanding a 1 in 2,500 year event, without sliding or separation at their bases, and therefore would not require any remedial or retrofitting works.
In January 2010, a $500 million scheme to repair, refurbish and repaint the bridge commenced, funded partly by the American Recovery and Reinvestment Act. On 8th June, the project was launched officially by New York mayor Michael Bloomberg (b.1942) and vice president Joe Biden (b.1942). It was completed in April 2016.
Repairs included replacing the steel approach viaduct decks with prefabricated concrete and steel grid slabs and increasing the capacity of the approaches from one lane to two, on both sides of the bridge. Overhead clearance at York Street arch over the Brooklyn Queens Expressway, on the Brooklyn approach was increased and some seismic retrofitting undertaken on the Franklin Square arch over Pearl Street, on the Manhattan approach.
Steelwork and roadway repairs were carried out to the bridge deck and the whole structure — main span, suspension cables, hangers and stays — repainted in ‘Brooklyn Bridge tan’ colour. The blasting and repainting took place inside enclosed units, preserving air quality by trapping and recycling the dust generated.
In 2017, work was underway to strengthen and widen the bridge’s elevated pedestrian and cycle walkway.
reference sources   Smiles3
Location

Blucher, Stephenson's first locomotive, site of