The 6th Street Bridge

The Harry Forden Bridge

What do you see in this picture? Do you see two stoplights preventing you from driving over nothing but an empty ditch? Do you see time spent waiting, time that wouldn't be wasted if this were a modern bridge? Or do you see a steel cathedral with a plethora of geometric shapes? Do you see a portal that for a few seconds takes you back to 1911, when the Model T was a new car, when the milkman's horse-drawn cart rumbled over its original wooden deck, when the Wilmington Insurrection of 1898 was a not-too-distant memory to citizens on both sides of this bridge? I suppose it all depends on your priorities. In any case, this bridge can be added to Wilmington, NC's list of charms: its historic homes, bumpy brick-paved streets, and towering houses of worship. It also stands as a relic from a time when it was not a ditch it crossed, but rather the Atlantic Coast Line railroad (or the Seaboard Coast Line after 1967), the Interstate 40 of its day.

When comparing this bridge to the recently constructed 5th Street Bridge (a.k.a. Thelma Bull Bridge), a basic concrete beam bridge, one can see how engineering has "evolved" from an art form to a perfected science. While the modern bridge gives you almost no indication that you are crossing it, the 1911 bridge, with its tall, narrow superstructure, gives the impression that it spans a greater distance than a mere 147 feet. Back when it was constructed, however, a structure made of smaller pieces put together, as opposed to one with a few heavy beams, was the most practical solution. The heavy equipment that is needed to lift large beams was more of a novelty at the time, while the human labor needed to assemble little pieces was more economical. Thus, without the aid of the computers and heavy equipment that are available today, the engineer of 1911 had to make dozens of pieces work together as a whole in order to accomplish the same purpose. The result: a work of art.

The configuration of this bridge is a relatively common one, the Pratt truss. Today most of the surviving examples of this once-prolific design are found on rural back-roads. It can be best distinguished by the straightness of the two uppermost horizontal beams, called the top chords, in conjunction with an "X" (or three, as in the case of this bridge) in the center of the span. The average turn-of-the-century or earlier Pratt truss one might see in a rural setting would have a more fragile look to it. The structural "members" of the bridge would be held together with pins. These bridges often have very narrow decks, and were thus meant to carry small amounts of traffic. This is not the case with this bridge, which features more robust design elements that are representative of its urban usage. It has stronger riveted connections and its diagonal members are beams, as opposed to light-duty steel rods as would be found on a rural bridge. It features a fairly wide deck, approximately 16.7 feet wide, which would allow for 8-foot lanes on each side. It was likely never sufficient to allow two motor vehicles to pass side-by-side, but this might have been possible for non-motorized traffic (the National Bridge Inventory, interestingly, lists it as a two-lane structure). The extra strength has allowed this structure to support a modern concrete deck (likely added in the 1978 reconstruction) while having a 22-ton single vehicle weight limit, more than the 3rd Street Bridge, which carries a far greater amount of traffic. When I was in the process of photographing the structure I observed several large SUVs cross through it; this certainly could not have been foreseen by the designers.

Nathan Holth (HistoricBridges.org) lists the three ways a beam can be "built-up," or stitched together into a single piece: latticing (the "X" pattern), v-lacing ("zigzag" pattern), and batons (square plates); all three are present on this bridge, adding to its interesting complexity. It also has suspended (or "cantilevered") sidewalks, hung off the side of the truss. The railing on the inside of the truss appears to be the original "latticed" type (or a reproduction); many truss bridges have been marred in appearance by the adding of modern guardrails. The railing on the wooden sidewalks is a simple modern type that was probably added for safety reasons. The bridge appears to have been kept in very good condition by the city of Wilmington, although there are some rust spots on the underside, notably around the lower chord connections that will hopefully be repaired some day.

If you look closely at the above picture you will notice that the two beams closest to the camera, the front posts, appear to be of unequal lengths. This isn't an illusion, but rather another one of the bridge's interesting design features, a response to a variable thrown in the designer's path (or improvised by the builder). The concrete abutments that the bridge rests atop sit at an angle on both sides, while the street has a straight alignment. These four integral members take this into account. The bar that the traffic lights are bolted to, along with the latticing above it (portal bracing), is bent in order to suit the difference in angles. The rest of the bridge, however, is straight.

In 2007 the bridge was dedicated to Harry Forden, a distinguished member of the Brooklyn community, which is located on the north side of the former tracks. I find it interesting that it took the city of Wilmington nearly a century to dedicated this notable bridge to a notable citizen.