Niagara Falls Suspension Bridge
Coordinates: 43 ° 6 ′ 33 ″ N , 79 ° 3 ′ 30 ″ W.
| Niagara Falls Suspension Bridge | ||
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| Official name | International Suspension Bridge (USA) Niagara Falls Suspension Bridge (Canada) |
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| use | Railway and road bridge | |
| Crossing of | Niagara River | |
| place | Niagara Falls (Ontario) / Niagara Falls (New York) | |
| construction | combined suspension and cable-stayed bridge , double-decker bridge | |
| Pillar spacing | 250 m | |
| Clear height | ≈ 72 m | |
| completion | 1854/55 | |
| planner | John August Roebling | |
| closure | 1896, replaced by Whirlpool Rapids Bridge | |
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The Niagara Falls Suspension Bridge was a two-story rail and road bridge over the Niagara River about four kilometers below the Niagara Falls . It connected the places Niagara Falls (Ontario) and Niagara Falls (New York) , which only appeared later under the same name, and thus also the USA and Canada . The bridge built by John August Roebling between 1851 and 1855 was not only the first permanent bridge over the Niagara River, but also the first suspension bridge in rail traffic and also the first of the large suspension bridges built by Roebling.
The bridge was commissioned jointly by two bridge construction companies from the two countries. It was given 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 area was used by people and wagons. 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 Rail Road . Since the three railway companies still had three different gauges at the time, the track originally consisted of four rails, so that the single-track bridge could be used by all trains.
history
To cross the 250 m wide and more than 70 m deep Niagara Gorge , only a suspension bridge came into question at that time, as all other types of construction were still a long way from achieving the necessary span. On the other hand, there was considerable controversy as to whether a suspension bridge could achieve the rigidity required for a railway bridge. First, Charles Ellet Jr., who had already built the Wheeling Suspension Bridge , was commissioned with the construction . In order to pull a rope across the raging river, he called a competition among the local youth to see who could pull a string to the other bank with his kite , which was actually successful after a few days. Ellet built a temporary suspension bridge on it, but soon got into serious financial disputes with his clients and finally left the project.
After a break of three years, John August Roebling was commissioned to build the bridge according to his ideas. Roebling had experience building aqueduct suspension bridges, had his own rope factory in Trenton, New Jersey and had already made offers for the original bridge. Roebling used Ellet's temporary bridge as a construction aid and completed his structure in four years. The bridge was officially opened on March 18, 1855 after the pedestrian deck had been in operation for a year. Roebling's completion report puts the cost of the bridge at $ 400,000, while a comparable British-style bridge with a box girder would have cost $ 4 million.
In his investigation report drawn up five years later, Roebling was able to prove that the bridge had survived unchanged and without any damage.
In 1886, as planned from the start, the wooden parts of the bridge were exchanged for parts made of iron and steel under the direction of Leffert L. Buck , which increased its load-bearing capacity. Since it was no longer able to cope with the increased traffic loads, it was replaced in 1897 by a steel arch bridge, also planned by Leffert L. Buck, which was initially called the Lower Steel Arch Bridge , later the Whirlpool Rapids Bridge .
Technical details
The suspension bridge - more precisely: a combined suspension and cable-stayed bridge - was supported by two pylons made of limestone , which were 27 m high on the American side and 24 m on the Canadian side and had foundations 8.5 m deep. Their pillar spacing was 250 m (821 ft 4 inches); the bridge deck between the pylons had a length of 244 m (800 ft). Two suspension cables with different sags were stretched over the cable saddles of the pylons on both sides and anchored behind the pylons in 16 m deep shafts. The suspension cables were parallel wire ropes ; each consisted of 3,640 wires that were produced on site using Roebling's patented air-jet spinning process . A total of 624 hangers were attached to the suspension cables to hold the track girder. In contrast to the recently completed Britannia Bridge by Robert Stephenson with its wrought iron box girder, Roebling connected the two road decks with a close-meshed lattice and thus achieved practically the same rigidity, but at significantly lower costs. In order to prevent major vibrations in any case, he also connected the pylons and the deck girder with 64 stay cables and stretched 56 cables from the deck to the slopes of the gorge. For safety reasons, Roebling had also set a maximum speed of 5 miles per hour (8 km / h) for the trains, although the tests before the opening had already shown that higher speeds were also easily possible.
Web links
- Final Report of John A. Roebling, Civil Engineer, to the presidents and directors of the Niagara Falls Suspension and Niagara Falls International Bridge Companies, May 1, 1855. Steam Press of Lee, Mann & Co., Rochester, NY 1855. Digitized on Digital bridges
- Report of John A. Roebling, Civil Engineer, to the presidents and directors of the Niagara Falls Suspension and Niagara Falls International Bridge Companies, on the condition of the Niagara Railway Suspension Bridge; August 1, 1860. Murphy & Bechtel, Trenton NJ 1860. Digitized on Google Books
Individual evidence
- ↑ Schweizerische Bauzeitung TEC21, May 23, 2014, No. 21–22, p. 28
- ^ M. Robinson: The Kite That Bridged The Niagara ( Memento June 18, 2008 in the Internet Archive ). Retrieved March 16, 2013
- ↑ Frank Griggs: Charles Ellet, Jr. ( Memento from April 19, 2012 in the Internet Archive ) (PDF; 846 kB) In Great Achievements, notable structural engineers , Structure magazine, October 2006.
- ↑ Information according to Roeblings Final Report