Chihuly Bridge of Glass

Aug. 24, 2004
The Chihuly Bridge of Glass, completed in 2002, initiated what has turned into a substantial partnership between Chihuly’s Studio and Pacific Lightworks, LLC of Portland, Oregon. Earl Levin, LC, IALD first began working with Dale in February 2000 to develop the lighting design concepts that now illuminate the artist’s glass installations for the pedestrian bridge in Tacoma, Washington. Later, Studio Director Mark Godfrey, LC, took the project to completion. In the early stages of concept development, we talked about the human experience of viewing Chihuly’s glass in a variety of changing conditions; intense daylight (clear sky), diffuse daylight (cloudy sky), transitional daylight (twilight) and no daylight (dark sky). We started by explaining to Chihuly’s team the physiology of the human eye and how changes in visitor visual response would require lighting solutions that respond to these changing conditions. Although each of the three elements (glass ceiling, towers, and vertical chambers) resided in close proximity to one another, each required uniquely different lighting solutions. The lighting and lighting controls (including skylight concepts and design, daylight tracking design, fiber optic head and cable design and mechanical cooling designs) for the three major glass elements presented a major esthetic and engineering challenge for Pacific Lightworks.The glass ceiling resided in a semi-enclosed environment. We introduced the concept of skylight slits rather than open skylights so we could use the benefits of both daylighting and a light box. We determined that an open skylight approach would leave no reflective surfaces for the light box. Skylight slits, on the other hand, required supplemental fluorescent lighting to maintain ceiling uniformity for sections shadowed by non skylight sections. To produce sufficient luminance for shadowed areas during these periods, a daylight tracking control system, using T-8 (100% to 1%) fluorescent dimming ballasts, was used. High color temperature, high CRI trichromium lamps were chosen in order to match daylight color temperature as closely as possible.During evening hours, as visitors became dark adapted, the amount of luminance necessary for viewing was reduced. As the daylight tracking photocell reduced fluorescent luminance, above ceiling halogen point sources, which were not effective during daylight hours, became active. This added depth and drama to the glass. The overall result was to produce two entirely different viewing experiences. This enticed visitors to return to the project at different times for completely different viewing experiences.The forty foot towers were made of a translucent blue plastic. Originally we planned to light the towers from the bridge. After doing several mockups, it was determined that this would be best done from the roadbed below. By removing the fixtures from the bridge structure, the towers became more isolated from other structures, allowing them to take on more stature. Standard metal halide lamps were chosen over ceramic because their spectral distribution provided a higher level of blue saturation for the tower elements.The vertical chambers were especially challenging. Because of security and environmental glass protection, access to the chambers was difficult. Although we would have preferred to light the glass with incandescent point sources for a much more dramatic effect, maintenance and access issues dictated that we use a fiber optic solution. To maintain specular brightness for three foot tall chambers stacked four high, we varied the number of fibers and the thickness of the fiber to account for light losses associated with fiber distance. Cleanliness and good cooling ventilation were also essential for the long term life of the fiber and the illuminators (30 in total). We introduced a flow through ventilation concept early on to achieve this objective.In the process of the long-term bridge design, Pacific Lightworks had the opportunity to work with Chihuly on other projects such as the Joslyn Window at the JoslynArt Museum in Omaha, Nebraska, and the Marlborough Gallery in New York City.Working on these projects, we learned that not all Chihuly glass is the same, varying in form, grain, texture and opacity. Each type of glass required special analysis for how a light source would be applied. Intensity of the source, lamp type, filtering and direction played a major role. Higher opacities required more frontal illumination to bring out the true intensity of the colors and show floating details. In some cases, backlighting was necessary to bring out the depth for a particular piece. Lensed HPL, PAR 64 and AR-111 lamps played a significant role for accomplishing many of our illuminance objectives.These projects greatly influenced our design concept for the bridge. They were the prelude for understanding the artist, his work, his people and the Chihuly culture, all key to successfully lighting Chihuly glass.Every Chihuly project is a happening. It is like opening day at a Broadway play. Quality and timing are everything if the play is to go on. With Dale, “could not be done” or “no” was not in his vocabulary; believe in yourself and nothing is impossible. We can only wonder what will be next.Earl F. Levin, LC, IALDPrincipal / Senior Lighting Designer PACIFIC LIGHTWORKS, LLC

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