Bahia Honda Rail Bridge - Structural Design

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 1938, 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.