Niagara Falls Suspension Bridge
43.109208 - 79.058336Koordinaten: 43 ° 6 ' 33.1 "N, 79 ° 3' 30 " W
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Niagara River
The Niagara Falls Suspension Bridge was a two-storey railway and road bridge over the Niagara River about four kilometers below Niagara Falls. She joined the later occurring under the same name places Niagara Falls (Ontario) and Niagara Falls (New York) and thus also the countries USA and Canada. Built by John August Roebling in the period 1851 to 1855 the bridge was not only the first permanent bridge across the Niagara River, but also the first suspension bridge in the railway and also the first built by Roebling large suspension bridges.
The bridge was commissioned by two bridge companies from the two countries together in order. It was called by different names such as International Suspension Bridge, Niagara Railway Suspension Bridge, Niagara Suspension Bridge or simply the Suspension Bridge.
The lower bridge deck at the level of the surrounding terrain has been used by people and carts. The upper deck had a track and thus served the trains of the New York Central Railroad, the Great Western Railway and the New York and Erie Railroad. Since the three railway companies at that time still had three different gauges, the track was originally composed of four rails, so that the single-track bridge could be used by all trains.
History
For the crossing of approximately 250 m wide and more than 70 m deep canyon at that time was only a suspension bridge in question, as all other types had by no means reached the required span. On the other hand, there was considerable controversy as to whether a suspension bridge could achieve the necessary for a railway bridge stiffness. First, Charles Ellet, Jr. with the building was commissioned, who had already built the Wheeling Suspension Bridge. To be able to ever pull a rope across the raging river, he called among the local youth organized a competition to see who could pull a string to the other side with his dragon, who was actually successful after a few days. Ellet built on a provisional suspension bridge, but soon ran into severe financial disputes with its customers and ultimately left the project.
After a break of three years finally got John August Roebling the contract to build the bridge to his ideas. Roebling had experience with the construction of Aqädukt - suspension bridges, had built its own cable factory in Trenton (New Jersey) and already made offers for the original bridge. Roebling used Ellet temporary bridge as Baubehelf and completed his building in four years. On March 18, 1855, the bridge was officially opened after pedestrian deck was already a year in operation. In Roebling's completion report, the cost of the bridge with $ 400,000 are estimated, whereas a similar bridge to British design with a hollow box would have cost $ 4 million.
In his five years later started investigation report Roebling was able to prove that the bridge had survived the period unchanged and without any damage.
In 1886, as already foreseen from the outset, exchanged under the power of Leffert L. Buck, the wooden parts of the bridge against parts of iron and steel, which increased their carrying capacity. Since she was finally no longer able to increase traffic loads, it was in 1897 replaced by a similarly planned by Leffert L. Buck steel arch bridge, which was at first, later called Lower Steel Arch Bridge Whirlpool Rapids Bridge.
Technical details
The suspension bridge was supported by two masonry of limestone pylons that were 24 meters high on the American side and 27 m on the Canadian side and had 8.5 m deep foundations. Your Pfeilerachsabstand was 260 m ( 821 ft 4 inches ); the bridge deck between the pylons had a length of 244 m ( 800 ft). About the cable saddle of the pylons were stretched on both sides two supporting cables with different slack, which were anchored behind the pylons in 16 m deep shafts. The supporting cables were parallel wire ropes; they each consisted of 3640 wires were produced with Roebling's patented air spinning process on site. On the carrying cables in total 624 trailers were attached to keep the track support. Unlike the recently completed Britannia Bridge by Robert Stephenson with its wrought-iron hollow box Roebling joined the two roadway decks with a close-knit truss grid, reaching practically the same stiffness, but at significantly lower cost. In order to prevent greater oscillations in any case, he also joined the pylons and the track support with 64 cable stays and tensed 56 ropes from the road deck to the slopes of the ravine. For security Roebling a top speed of 5 miles per hour had also for the trains (8 km / h) has, although the tests had already shown before the opening, that higher speeds were readily possible.