LED Fixtures Sparkle Like Jewels on the Mid-Hudson Bridge
On a cold night in December 2000, a few fearless cable walkers from the New York State Bridge Authority were climbing atop the Mid-Hudson Bridge, a graceful suspension span that crosses the Hudson River between Poughkeepsie and Highland, NY. The climbers were hanging custom-designed lighting fixtures for a partial mock-up of what would become a sparkling new lighting scheme for the 72-year-old bridge.
By September 2001, when the lights were actually turned on, a total of 142 fixtures were installed, creating a necklace of lights strung along the cables of the bridge, whose towers stretch as high as 315' (95m) above the water. These outdoor fixtures combine a weather-proof housing manufactured by MagniFlood of North Amityville, NY, with the color-changing Chromacore® LED technology by Color Kinetics in Boston, MA.
“We got the two manufacturers together,” says Joe Rosa, project manager for Baker Engineering, the Elmsford, NY, firm that served as consulting engineer and de facto lighting consultant for the project. “MagniFlood had a necklace-style lighting fixture that was weathertight and very durable. We worked with them to come up with a version of this fixture that would accept the guts of the Color Kinetics LED electronics. We provided them with the technical information and had to make sure it was all compatible.” There are 192 LEDs in each MagniFlood fixture.
On the night of the mock-up, six fixtures were hung 20' (6m) apart on the suspender cables that run from the main cable of the bridge to hold up the roadway. “Once we stood back and took a look at them, we decided that the fixtures should be spaced 40' (12m) apart, or on every other cable,” says Greg Herd, manager of information technologies for the New York State Bridge Authority, who took an active role in the lighting of the bridge. “This gives a more majestic look to the system.”
Once the placement issue was decided, Baker Engineering worked on the method of installation. “We added a messenger cable, which is actually a wire rope, to support the data cables and power cables for the fixtures.” The wire messenger cables allow for clamps to be placed every 6' (1.8m) to attach the power and data cables, all of which are grounded. The cables run to the fixtures which are attached to handrail stanchions on the suspension cables of the bridge. “The stanchions line up exactly with the suspender ropes,” Baker notes.
Data distribution for the LEDs is via a modem and 1300-NM single-mode fiber-optic cable that runs a quarter-mile (0.4km) from a control room in the Bridge Authority's nearby administration building to the bridge itself. “There was fiber-optic cabling already installed for the intelligent signage on the bridge,” explains Baker. “We were able to use a spare strand of that fiber.”
Herd, who had once done lighting design for local bands in upstate New York, took an active interest in the programming of the lights, using Color Kinetics' ColorPlay® software. “I had used some CAD programs, and in playing with this software found a similarity in using lights instead of lines,” he says. In programming the light shows for the bridge, Herd discovered he had more flexibility if he used a standard PC with Windows 2000 and downloaded the shows to Color Kinetics' iPlayer® storage and playback device.
To date, Herd has programmed approximately 100 light shows for the bridge, all of which are stored in the lighting system's control computer. “The sky is the limit,” he says. “We can store an unlimited number of shows and the iPlayer acts as an interface. I launch a show on the computer and the iPlayer kicks in. At first we thought we'd program a show and download it into the iPlayer and leave it at the bridge. But we decided the fiber was a better option,” Herd adds. “The advantage is that we have instantaneous control from the office.”
With his computer skills also kicking in, Herd has invented a few new ways to use the ColorPlay software. First, he can use any telephone or cellular phone to launch a limited number of pre-programmed shows. “The hardware and software I am using for this allows me to access up to 256 stored shows,” he explains. “I can go in and identify a combination of numbers on the keypad to launch a certain show.”
Herd's second option is to launch any of his pre-programmed shows via internal web pages served from the company's intranet site, which also delivers live video feeds from cameras on the bridge that provide a real-time look at the lighting. These pages can also be accessed from a wireless Compaq iPaq handheld computer. The Bridge Authority's public website (www.nysba.net) includes facts and photos of the bridge fully lit.
The various shows range from color-coordinated holiday programs with restrained movement and slow fades, with fancier movement saved for special occasions such as fireworks displays. “People are driving across the bridge and we try to keep distractions to a minimum,” explains Mark Sheedy, director of planning and public relations for the New York State Bridge Authority. One of these special occasions will be June 1, 2002, when the lights on the bridge will “dance” in time to the music of a fireworks display planned as part of a hot air balloon festival in a nearby park.
“One of the main reasons we went with this system was maintenance,” Sheedy notes. “There are risks when people go up on the cables, so we needed a fixture where all the parts are easy to swap out.” To meet this need, MagniFlood provided a light with tool-free replacement parts. “We also wanted a low-voltage solution that was different from the standard white incandescent light, so we were happy when Baker suggested the LED solution.”
An interesting aspect to this story is that the Poughkeepsie Area Chamber of Commerce had approached the Bridge Authority over 10 years ago and asked about adding necklace lighting to the span. “At that time we lit just the steel towers,” explains Sheedy. “Jack Gaffney, our executive director, asked that we explore other options for lighting the cables. It works out that the authority did not move ahead then. By waiting we got a better system that is cost-effective and more energy-efficient.”
The roadway of the bridge is lit with standard high-pressure sodium fixtures, and the towers are lit at the roadway level only. Baker Engineering has a contract to go back and add floodlights to illuminate the base of the towers and add fixtures at the tops of the towers as well, giving the bridge nice, even lighting as a backdrop to the “jewels” hung on the cables. “The LEDs do not illuminate the bridge, but act as special accents that glow intensely in the selected colors,” notes Mike Blackwell, senior engineer at Color Kinetics, who also had a hand in the success of this project.
The new color-changing lighting system was meant to be illuminated for the first time on September 15, 2001, at a celebration where New York Governor George E. Pataki would pull the original switch dating from 1930 when the bridge was inaugurated. “On Tuesday, September 11, we cancelled the celebration,” says Sheedy. “On Wednesday morning we decided to just turn the lights on that night without any fanfare.” And on they went, in a red, white, and blue patriotic theme that matched the mood of a nation coming to grips with a brave new world.
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