[andyhaus1057]

I have been able to compile this information for my history class, and there are a few questions that I need to answer. Can you help me with these?

a) Why was Eads Bridge important when it was constructed?

b) What was the use of Pneumatic caissons and what Eads did with them?

c) Tell about the cantilevered approach to building the bridge and why it was used

Eads bridge was the first bridge to be built using cantilever support methods exclusively, and one of the first to make use of pneumatic caissons. The Eads Bridge caissons, still among the deepest ever sunk, were responsible for one of the first major outbreaks of "caisson disease" (also known as "the bends").

The Eads Bridge is still in use, and stands on the St. Louis riverfront between Laclede's Landing on the north and the grounds of the Gateway Arch to the south. Today the road deck has been restored, allowing vehicle and pedestrian traffic to cross the river. The rail deck has been in use for the St. Louis MetroLink light rail line since 1993.


The Bridge was conceived as a solution to the futile quest to reverse this new found eminence. The bridge, generated in controversy, was also considered a radical design solution, though the ribbed arch had been a known construction technique for centuries. The triple span, tubular metallic arch construction was supported by two shore abutments and two mid-river piers. Four pairs of arches per span (upper and lower) were set eight feet apart, supporting an upper deck for vehicular traffic and a lower deck for rail traffic.


Construction involved varied and confusing design elements and pressures. State and federal charters precluded suspension or draw bridges, or wood construction. There were also constraints on span size and regarding the height above the water line. The location dictated a change from the low Illinois floodplain of the east bank to the high Missouri cliff on the west bank of the river.


The particular physical difficulties of the site stimulated interesting solutions to construction problems. The deep caissons used for pier and abutment construction signalled a new chapter in civil engineering. Unable to construct falsework to erect the arches because they would obstruct river traffic, Eads's engineers devised a cantilevered rigging system to close the arches.

Although recognized as an innovative and exciting achievement, the Eads Bridge was overcapitalized during construction and burdened with debt. With its focus on the river, St. Louis had a lack of adequate rail terminal facilities, and the bridge was poorly planned to coordinate rail access. An engineering and aesthetic success, the bridge was bankrupt within a year of opening.

Granite for the bridge came from the Iron County, Missouri quarry of Missouri Governor and U.S. Senator B. Gratz Brown who hadhelped secure federal financing for the bridge.


The Merchants Exchange eventually lost ownership to the Terminal Railroad Association of St. Louis. The Exchange, fearing a Terminal Railroad rail monopoly on the bridges, would then build the Merchants Bridge (which in turn would eventually be taken over by the Terminal Railroad. The Terminal Railroad transferred the bridge to the City of St. Louis in 1989 in exchange for the MacArthur Bridge.



In 1998, the Naval Facilities Engineering Service Center investigated the effects of the April 4, 1998 ramming of the bridge by the barge Anne Holly. The ramming resulted in the near breakaway of a riverboat casino ; several recommended changes reduced the odds of this happening in the future.



This three span, ribbed steel arch bridge (1874), with an overall length of 6,442' and a clearance of 50 above high water, rests on piers that rise 193' (east) and 113' (west) from bedrock. It was designed and built by Captain James B. Eads (1820-1887), who utilized an innovative cantilever support to produce spans larger than any previously constructed. The largest bridge of its time, it linked railroads running east from St. Louis, Illinois, with those going west from St. Louis, Missouri


On-going risks with the structural integrity and removal of masonry towers on the east shore make the NHL severely unstable and threaten the safety of the adjacent railroad and street. Also, multiple ownership associated with the bridge's historic uses for vehicular as well as (light) rail transportation is still a cause for concern due to the lack of clear division and assignment of responsibilities for the maintenance of the structure itself. A preservation plan or programmatic agreement assigning responsibility would be an appropriate solution.

The upper deck of the structure opened to pedestrian traffic on July 4, 2003 after decades of pedestrian traffic restrictions. Funds were raised by Trailnet, Inc. a local bicycle nonprofit. The AASHTO - compliant railing was installed. This sympathetic design was based on construction drawings of railing installed in 1874, but missing for a half century. Proposals for plumbing lines to provide water to the upper deck for use during summer festivals were submitted to the MO SHPO by the city's Board of Public Service. These proposals were reviewed by the SHPO under Section 106 and altered to reduce any potential damage to bridge's stonework.

[Clough]

I guess that I'm very much like a dad who is trying to help his son, andyhaus1057.

Please see my post on the following thread via clicking on the following link.

Thanks!

https://www.askmehelpdesk.com/baseba...me-274737.html