Benjamin Franklin Bridge
As part of a project to relight the Benjamin Franklin Bridge in honor of the 2000 Republican Convention, we were asked to restore the historic lanterns on the bridge, all originally manufactured by the Smyser-Royer Company of York, PA. This was no easy task. The largest is a cast iron behemoth that is ten feet tall and weighs in excess of one thousand pounds. To shield against persistent vandalism, the maintenance department had wrapped the fixtures with sheet metal covers. This protected the lanterns from the vandals but trapped moisture inside. We had no idea what these fixtures looked like behind the protective shrouds, but we were about to find out
The moisture trapped inside over a thirty year period caused such severe rust that some involved with the project had reservations about the restorability of these lanterns. It was clear that we had our work cut out for us!
The disassembly process was grueling. The sheer weight of working with cast iron is exhausting but the fact that every piece was rusted and/or painted to the adjacent part was even worse. Yet we couldn't use too much force for fear of breaking the brittle cast iron. Each break meant another weld for us to perform, or worse, some of the pieces had already broken years ago, and some pieces had to be re-cast.
Once disassembled, we started on rust removal: a chemical stripping of the paint, followed by rust removal. Once we were down to the base metal we could start the repair process. First, the grinding and welding of the cracks and broken pieces, then the fitting of the frames. Another problem: we had marked the frames because they did not interchange but the stripping process had obliterated most of our markings, so it was trial and error fitting. We also had to remove many broken-off bolts and re-tap the holes.
The paint finish was to be the same system used in the current repainting of the bridge: a three component system comprised of a zinc rich primer, an epoxy mid-coat and a polyurethane top-coat. each part had to be handled six times, three each for inside and out for each step. A lot of work considering that, not counting the frames, each parts weighed between 75 and 400 pounds each.
To thwart the vandals somewhat, we wanted to use polycarbonate lenses but the lighting designer wanted to use white Lumasite, a fiberglass reinforced acrylic with excellent diffusing abilities. However, Lumasite isn't bendable and we had a curved fixture. The solution was to use clear polycarbonate outer shield and a .062 thick Lumasite panel which would flex into position and be held in place by the clear panel. The mounting of a 100 watt metal halide lamp provided the ideal level of illumination.
We opted to ship the mounting arm separate from the lantern. This simplified handling on our end and installation for the contractor. this allowed us to ship the fixtures in such a position as to not damage the paint finish. For more information on the project, visit http://lightingdimensions.com/ar/lighting_crossing_delaware/
We would like to thank Dan Edenbaum of Grenald, Waldron Associates for allowing us to perform this restoration.