User:Sean.bailey00

''This page created to fulfill assignment 6 for Johns Hopkins University's EN560.141 "Perspectives on the Evolution of Structures". For the current article on the Bahia Honda Rail Bridge please follow this'' link.

The Bahia Honda Rail Bridge is a disused bridge in the lower Florida Keys connecting Bahia Honda Key with Spanish Harbor Key. Originally part of the Overseas Railway, the State of Florida purchased it after the 1935 Labor Day Hurricane and converted it to provide automobile use as part of the Overseas Highway in 1938. After a replacement Bahia Honda Bridge was opened in 1972, two spans of the bridge were removed to accommodate boat traffic and make the majority of the bridge inaccessible to pedestrian traffic, but the rest remain standing.

History
It was originally built by Henry Flagler as part of the Overseas Railroad which was completed in 1912. Flagler funded the construction of the bridge, along with the rest of the railway himself. It was purchased by the state of Florida and converted for highway use in 1938 after the Labor Day Hurricane of 1935. Rather than completely rebuilding the bridge after the hurricane, the existing structure was repaired and the deck for the Overseas Highway was added on top, as the existing deck inside the truss was too narrow for vehicular traffic. The bridge served as the primary mode of transport to the islands of the lower Keys, and as a primary evacuation route.

A new four-lane bridge was built in 1972, a few hundred yards north of the old bridge, replacing the old route of U.S. 1. Today, the former bridge provides a scenic overview of the area for tourists. Two of the truss spans have been removed in order to facilitate boat traffic, as the new bridge has an increased span height. The original bridge has fallen into a state of disrepair and signs have been posted on the bridge warning boat traffic to watch for falling debris, but all of the sections have remained standing (not counting the two that were removed). The easternmost section remains open to pedestrian traffic and is maintained by Bahia Honda State Park.

Structural design
Before its re-imagining as a vehicular bridge, the Bahia Honda Rail Bridge was intended to carry a single track of the Florida East Coast Railway across Big Spanish Channel from Bahia Honda Key to Spanish Harbor Key. Unlike most of the other bridges on the Overseas Railway, the Bahia Honda Rail Bridge has a steel truss construction. This was a necessary difference from the predominate concrete arch form of the other bridges of the overseas railroad, as the channel is the deepest of those spanned, at 24 feet. The central span is a Parker truss with a span of 247 feet. This is surrounded by 13 Pratt truss sections spanning 186 feet on either side, and 13 smaller Pratt trusses each spanning 128 feet outside those. Nine plate girder sections were used for the western approach, for a total length of 5055 feet. The smaller Pratt trusses have riveted connections, but the larger Pratt and Parker trusses use pinned connections, making the Bahia Honda Rail Bridge the longest pin-connected truss bridge in the United States.

In 1972, the bridge was re-purposed to carry two lanes of U.S. Route 1. Rather than undertake the costly project of rebuilding the entire bridge, the road deck was added on top of the trusses, as the through-truss construction of the original deck meant that its width could not be expanded. Thus, the bridge became a deck-truss bridge, and remains one of the only Parker deck-trussed bridges in the country.

The original construction of the bridge was carried out by William Krome and Joseph Meredith, and the vehicular conversion was undertaken by B.M. Duncan.

Qualifications as structural art
The Bahia Honda Rail Bridge has several features that align with the scientific, social, and symbolic criteria that define structural art. From a scientific point of view, the bridge efficiently met its original design goal of carrying a single rail line across a relatively long span with a stiff steel truss design. When the bridge was converted into a vehicular bridge, rather than building an entirely new bridge, a deck truss was added to the existing spans, accomplishing the task of re-opening the Keys in as quick and inexpensive method possible. The social impact of the bridge was enormous. Along with the other bridges of the Overseas Highway, the Bahia Honda Rail Bridge was integral in providing a link to and from the Keys - not only for traffic, but also for water and electricity. Its conversion made it even more integral for the Keys, especially as an evacuation route. This was an important consideration in the wake of the devastating Labor Day Hurricane of 1935. All of those benefits came at a rather low price to the people of Monroe County, as Henry Flagler initially funded the bridge's construction, and the economic benefits have been immeasurable. As a symbol, the entire Overseas Highway has come to define the Keys, and the lightness and elegance of the form of the Bahia Honda Bridge in contrast to the heavier reinforced concrete arch bridges that populate the rest of the Keys makes it a particularly memorable link to the lower Keys.