This attractive pony truss adds much beauty to its surrounding environment. The bridge features built-up members including v-laced vertical members, and diagonals utilizing battens. Overall this is an excellent example of pony truss technology from the first couple decades of the 20th century. In 2006, although damaged in some areas, this bridge did still retain original lattice railing as well. Also in 2006, a concrete deck with curb was present, although this curb had broken up at one end.
By 2010, this deck had been replaced with an open steel grid deck system. Steel grid decks are sometimes used on metal truss bridges because they are durable and require little maintenance. They can sometimes cause a problem on bridges which receive winter deicing salts, because they do not allow for the directing of the corrosive salt into a drainage system, instead allowing salt to drip through the deck and come in contact with the flooring system of the truss. However, this should not be a problem on Napier Road, which is a rural dirt road that should not see winter salt.
Unfortunately, during the deck replacement project, the attractive original lattice railings were also removed and replaced with modern Armco style guardrails, which are mounted directly on the truss web. The purpose of this action is unclear. The Armco guardrails might reduce the amount of paint a car loses that might collide with the bridge, because the Armco guardrail has a smoother surface. However, because the Armco guardrails were mounted directly to the truss web, they provide no other additional benefit over the lattice railings in terms of protecting the bridge. Any impact damage delivered to the guardrails will be directly transferred into the truss web. If the impact is strong enough to bend or crack any part of the truss, the structural integrity of the bridge will be seriously compromised.
HistoricBridges.org (and many engineering firms as well) have always recommended that any modern guardrails added to a heritage truss bridge like the Napier Road Bridge be mounted to posts which are attached to the deck, so that impact forces are transferred to the deck, where they will have a minimal effect on the structure and prevent damage to the truss web. HistoricBridges.org always further recommends that when modern guardrails are added, that the original railings should be left in place, because these original railings contribute to the historic integrity of the bridge as well as its aesthetic qualities.
Aside from deck surface replacement, no other major work appeared to have been done to the bridge during that project. A good followup project to the deck replacement would be to repaint the truss superstructure, since areas of rust are visible on the bridge. Repainting the bridge would ensure that this rust does not begin to cause deterioration in the form of section loss and pack rust. Also, the guardrails should be corrected as described above. Once the bridge is repainted and the guardrails fixed, then routine maintenance should keep this historic structure around for many decades to come.
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