Thousand Islands Bridge

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Coordinates: 44 ° 20 ′ 51 ″  N , 75 ° 59 ′ 1 ″  W.

Thousand Islands Bridge
Thousand Islands Bridge
Thousand Islands International Bridge as seen from the Skydeck on Hill Island
use Road bridge
Convicted Interstate 81 , Highway 137
Crossing of Saint Lawrence River
place Wellesley Iceland ( New York ) and Hill Iceland ( Ontario )
construction Suspension bridges , arched bridges, steel truss bridges
start of building April 30, 1937
opening August 18, 1938
planner Robinson & Steinman
location
Thousand Islands Bridge (New York)
Thousand Islands Bridge

Thousand Islands Bridge is the collective term for a total of 13 km long series of bridges and roads that connect the United States and Canada through the Thousand Islands and across the Saint Lawrence River . It is the first bridge connection over the St. Lawrence River below Lake Ontario ; the next bridge is the Ogdensburg-Prescott International Bridge, some 60 km further downstream .

location

On the US side, the starting point is the intersection of Interstate 81 with New York State Route 12 at Collins Landing ; on the Canadian side, the intersection between Ontario Highway 137 and the Thousand Islands Parkway or Ontario Highway 401 .

General

All bridges except the two short border bridges are two-lane steel bridges on concrete foundations, designed by Robinson & Steinman and built in 1937/38. The steel parts are in the typical green preferred by David B. Steinman, which contrasts with the yellowish-brown concrete of the foundation pillars. The bridges have narrow walkways delimited by guardrails, but these are only open in the summer months.

Initially 150,000 vehicles drove over the Thousand Islands Bridge, which is subject to a toll, today it is around 2,000,000 vehicles.

The Thousand Islands Bridge and its surroundings are operated, serviced and maintained uniformly by the Thousand Islands Bridge Authority on the basis of an American-Canadian agreement.

Wellesley Island Suspension Bridge

The Wellesley Island Suspension Bridge begins immediately after the toll station on the US side and leads Interstate 81 over the American arm of the river to Wellesley Island. It is a total of 1,372 m long suspension bridge with 76 m high pylons , a main span of 244 m (800 ft), the two 564 m long ramps and a clearance height of 45.72 m (150 ft). Striking are the stay cables attached in addition to the vertical hangers in the longitudinal direction between the suspension cables and the bridge deck, as well as frames made of narrow steel girders suspended between the suspension cables and stiffened by diagonal cables. Also unusual is the anchoring of the suspension cables, which are fanned out into their 37 individual strands just before the anchor blocks and each strand is individually attached to the anchor block via an adjustable socket.

Wellesley and Hill Islands Bridge (border bridges)

The Wellesley and Hill Islands Bridge crosses the narrow arm of the river known as the International Rift , which forms the state border. It is a concrete segment arch bridge that is only 27 m long and is clad with masonry. Because of the lack of space in front of the border station, an identical three-lane bridge was built next to it in 1959. From the border, the road now called Highway 137 leads through Hill Island.

Hill and Constance Islands Bridge

The Hill and Constance Islands Bridge is a 183 m long Warren girder truss bridge, which leads from Hill Island to Constance Island and is supported in the middle with a pile yoke made of reinforced concrete on a tiny rock island.

Constance and Georgina Islands Bridge

The Constance and Georgina Islands Bridge is a steel arch bridge a few meters after the truss bridge. It has a wingspan of 106 m (348 ft).

Georgina Island Bridge

The Georgina Island Bridge is a suspension bridge over the northern arm of the St. Lawrence River, which shares a reinforced concrete pile yoke with the steel arch bridge, at the base of which the anchor blocks of the suspension cables are located. It has 62 m high pylons and a total of 404 m long, has a main span of 229 m (750 ft) and a clearance height of 37 m (120 ft). As with the Wellesley Island Suspension Bridge, there are also additional stay cables and frames between the suspension cables and the same anchoring of the suspension cables with the fanning out of the 37 strands.

history

The two suspension bridges represent a striking point in the development of this design. Leon S. Moisseiff had developed the deflection theory , which goes back to Joseph Melan , and applied it for the first time in the Manhattan Bridge, which opened in 1909 . This new static calculation method made it possible to build suspension bridges that were much lighter and consequently cheaper and quicker than before. In the years that followed, the deflection theory was further developed by numerous engineers, including David B. Steinman. One of the views developed from it was that flat bridge decks were more suitable than the high truss structures that were customary up to now, as they offer less resistance to the wind. The deflection theory and the meanwhile improvements in the steel quality now made flat bridge decks made of plate girder structures possible for bridges that run high above the water.

The construction of a bridge over the St. Lawrence River had been discussed since 1920, but repeatedly failed due to financial problems. In 1932, Robinson & Steinman was commissioned with a design by private initiatives, and the Thousand Islands Bridge Authority was founded the following year. In 1934, David B. Steinman submitted a design that was as close as possible to the tight financial framework and provided for exceptionally light suspension bridges with flat plate girder decks. The groundbreaking ceremony finally took place on April 30, 1937. The entire project was completed in just 16 months - 10 weeks before the agreed deadline. On August 18, 1938, the opening ceremony took place with President Franklin D. Roosevelt and Prime Minister Mackenzie King .

At the end of the construction period, vibrations in the bridge decks had already been noticed, which were up to 61 cm high depending on the wind direction. As a temporary measure, Steinman had diagonal stay cables installed, which dampened the vibrations but shortened the wavelengths. Eventually a system of stay cables and stiffeners was installed that eliminated the problems. This experience, which he also had with the similar problems on his Deer Isle Bridge , which was only completed shortly afterwards , led him to the realization that the generally accepted deflection theory in its form at the time did not take into account the aerodynamic effects of the wind at all - which was shortly afterwards due to the The collapse of Moisseiff's planned Tacoma Narrows Bridge on November 7, 1940 was proven. David B. Steinman responded by providing the Mackinac Bridge, which was built from 1954 to 1957 and is regarded as his life's work, with extremely deep and stiff girders made of wind-permeable half-timbered structures.

Web links

Commons : Thousand Islands Bridge  - collection of pictures, videos and audio files

Individual evidence

  1. Gerhard Mehlhorn (Ed.): Handbook Bridges: Designing, Constructing, Calculating, Building and Receiving . 2nd edition Springer-Verlag Berlin Heidelberg 2007, 2010, ISBN 978-3-642-04422-9 . P. 69
  2. Tadaki Kawada: History of the Modern Suspension Bridge: Solving the Dilemma Between Economy and Stiffness . ASCE Publications, Reston, Virginia 2010, ISBN 978-0-7844-1018-9 . P. 104 f
  3. ^ A b c Richard Scott: In the wake of Tacoma, suspension bridges and the quest for aerodynamic stability . ASCE Press, Reston, Va. 2001, ISBN 0-7844-0542-5 , p. 35 ff

See also