Dynamic Lighting for Historic Infrastructure
The Three Sisters are three similar self-anchored suspension bridges built in the 1920s spanning the Allegheny River in downtown Pittsburgh, Pennsylvania. The bridges have been given formal names to honor important Pittsburgh residents, Roberto Clemente, Andy Warhol, & Rachel Carson.
In 2023, Allegheny County wanted to add permanently installed accent lighting to the iconic bridges. The project was a design and supply based effort with Eric Ridings at engineering firm Michal Baker International1 serving as the project and engineering manager in charge of lighting specification. Eric chose SGM Light as his partner to develop and deliver the lighting solution for the bridges.
"At every interaction, the people at SGM have been terrific. They know their products inside and out and understand the realities of field conditions, particularly valuable given how much of this installation had to be done from a barge. SGM Network Admin software is intuitive and user-friendly. The VPL fixtures are virtually plug-and-play and allowed us to feature the steel eye-bars both statically and through subtle video-to-light animations. The broad range of wash lights was perfectly suited for the long throws on the icon towers and the shorter highlighting the newly restored stone piers, as well."
David Nash
Integrated Theater Systems, Principal
The project required a durable fixture that could attach to the I-bar supports of the bridge to deal with the harsh Pittsburgh winters. Dynamic pixel segments allowing control of each 3” section individually were desired to provide dynamic color sequences that were not possible in the past.
Additionally, high power SGM P-10 and Q-10s color-changing LED fixtures mounted to the I-bar supports and the north and south river sides were selected to light the 78-foot towers. The extra power of the 10 series was required so that the bridge towers, painted bright yellow, could be lit in any color.
Each bridge is controllable separately using a controller capable of up to 25,600 individual channels.
An addition to the bridge steelwork, lighting was added to each of the supporting bridge piers. This was accomplished using 8 wide angle RGBW flood lights mounted to the bottom of the road deck and aimed at the piers. In white light, they show off the beautifully restored stone work, but also allow more creative looks with their full color capabilities.
Each of the bridge’s i-bar supports is finished off with a direct view necklace light which allow the blue color from the old bridge lights to stay or the addition of a full gamut of color changing.
1 Michael Baker International is a leading provider of engineering and consulting services, including design, planning, architectural, environmental, construction and program management, based in Pittsburgh and with more than 85 offices nationwide. They partner with clients on everything from roads, bridges, tunnels, mass transit, and airports, to water treatment plants, arctic oil pipelines, environmental restoration and specialized overseas construction.
Products used
P-10s
Q-10s
VPLs