Night Lighting on Bridges
Almost all bridges are lit at night, making the bridge a prominent public artwork and attractive part of the cityscape at night. Many different methods are used, just as different methods are used to light a play onstage.
The earliest method was to floodlight the structure with white light from a distance, so that it can be seen at night much like it is during the day. A variation on this method is to place the light sources within the structure, so that it highlights either the structural framework or the decorative elements of the bridge from unusual angles. White lights within the towers of the George Washington Bridge highlight its industrial, erector-set structure. On the 1768 Bristol Bridge over the River Avon in central Bristol, England, a yellow light is hidden behind columns facing the beige sandstone of the spandrel, resulting in a golden halo effect that complements the deep royal blue color of the deck girder. A third method, commonly done on suspension bridges, is to highlight the curved suspension cables by lining them with small, outward-facing lights. In this case, the purpose is not to illuminate the bridge structure itself, but to highlight the form by outlining it.
In each of these early cases, the lighting is white or pale yellow. However, a fourth method, starting to become increasingly common, is the use of deeply colored lighting. Like white lighting, colored lighting can be applied as a wash from the outside of the structure, hidden within, or faced outward from the cables and towers. The early examples involved a broad wash of a single color to illuminate modern, sculptural cable-stayed bridges at night. The purple angled cables of the Zakim Bridge are now a prominent landmark in downtown Boston. Even cement pier bridges, which have no towers or cables, can be lit at night. Cement, which is generally white or beige in color, is a perfect blank canvas for colored lighting.
I will be adding more brightly lit bridges to this gallery every few weeks. There is also a detail description of the lighting of bridges in my book, Bridgespotting: A Guide to Bridges that Connect People, Places, and Times.