by Claire Swedberg
Electrical Contractor Magazine
Published: July 2010
All Bright Electric installs LEDs to illuminate one of the world’s longest walkways
The 6,800-foot bridge over New York’s Hudson River dates back more than a century when it served as the Poughkeepsie-Highland Railroad Bridge. It now is used as a walkway. But the lights that illuminate the walkway, and the security system to provide assistance to those crossing its expanse, have had a much shorter lifespan. In fact, All Bright Electric only completed the lighting installation in March 2010. All Bright also installed surveillance cameras, a suicide-prevention phone and speaker system on the bridge.
The Walkway Over the Hudson project was launched in August 2009 and included installation of state-of-the-art light-emitting diode (LED) illumination the entire length of what is one of the world’s longest foot bridges. The LEDs wash the walking surface with light, without creating light pollution to the area above and around it.
All Bright Electric bid on and won the $700,000 electrical-installation job, which also included public safety technology. The sheer size of the project, requiring lighting to extend more than a half-mile from each end of the bridge, was not the only thing that made this task unique. The Walkway Over the Hudson board had also decided to proceed with a new type of LED tube, Illumatube, invented by local lighting company Litgreen, Poughkeepsie, N.Y., owned by lighting designer Andy Neal.
The walkway bridge project itself was envisioned many years ago, said Mike Duffy, walkway construction coordinator.
First built for the railroad in 1889, the steel cantilever bridge was considered an engineering marvel at the time. It went out of service in 1974 and stood unused for decades, although it was listed on the National Register of Historic Places in 1979.
The local nonprofit Walkway Over the Hudson acquired the bridge in 1998 and pursued funding for the walkway concept that would allow pedestrians and cyclists to cross the Hudson and enjoy what would become New York’s Walkway Over the Hudson State Historic Park. A study was conducted in 2007, and work began a year later. Altogether, the Walkway Over the Hudson raised $32 million, and workers completed some metal repairs, added concrete panels and built railings, all over the course of about two years.
In 2009, as the official opening approached, Walkway Over the Hudson received a grant to install lighting. While the group considered a variety of options, Neal proposed something more innovative. He had developed 4-foot fluorescent tubes with LEDs on a circuit board inside the tube. The tubes act both as the shield and conduit for these energy-efficient lights.
By rotating the cylinder in the direction of the light, it could be adjusted to point directly down on the bridge, reducing any light pollution and meeting the Department of Transportation’s Dark Sky Initiative guidelines. “The goal was to light the deck without creating any glare in the eyes,” Neal said.
The installation comprises a total of 86,000 lights in 423 tubes, with those tubes bundled into 43 sections, each consisting of a 480-volt, three-phase (conductor) power system.
“No one’s ever done anything like this before,” Neal said.
The system also uses a fraction of the energy required for traditional lighting; about 9 kilowatts would run the whole bridge. In the future, Neal said, the installation lends itself to renewable power at 24 volts.
In the case of the walkway, All Bright Electric’s task was to install the LED lighting on the southern side only of the bridge, yet illuminate the 24-foot-wide bridge across its entire expanse and be visible from both sides of the bridge. The lighting runs behind the hand railing, ensuring it does not protrude into the walkway and pose a problem for the movement of kids, wheelchairs and bicycles. The tubes were installed outside the bridge; therefore, they needed to be sturdy enough to sustain abuse from weather, accidents or vandals.
To make this happen, 11 All Bright electricians ran conduit on the outside of the bridge using articulated lifts to support them during the installation, suspended 220 feet above the river.
“The lighting was a hell of a technical challenge,” Neal said.
Electricians installed the lights every 16 feet in 4-foot blocks, with 12-foot breaks between, spreading the light in such a way that there is at least a half foot-candle everywhere on the bridge. The lights were angled down at 15 to 20 degrees toward the decking.
There were several challenges related to powering a string of LEDs this long. The power would be supplied from both sides of the bridge and meet in the center. There would be 43 24-volt power supplies, each of which splits into two, so that 72 feet goes one way and 72 feet goes the other. All Bright Electric and Litgreen found that the inrush of current would be too high when the power was turned on. So to limit it, All Bright Electric made a design adjustment that involved setting up relays on each power supply with a timer to create a cascading effect of illumination, which reduces the initial inrush. In addition, the system of cascading relays allows the parks to use different on/off lighting schemes in the future.
The lighting system, now in use on the bridge nightly, creates a red-yellow glow that washes the walkway with warm light, which reflects off the concrete in such a way that a pedestrian or cyclist can fully see the ground and still enjoy a starry sky above without glare. The bridge lighting ceremony was held May 15, 2010.
Working on other walkway systems
All Bright Electric also handled the installation of other systems on the bridge project. One such system was a lightning protection system. For lightning protection, All Bright Electric installed 140 spots of grounding across the length of the bridge. Because the rails of the bridge fit one inside another in sections, there was no steel continuity, so it required a series of grounding points that All Bright Electric provided in the form of pneumatic pins. These pins were shot into the bridge with a stud on which the conduit strap was mounted. A total of 5,250 shots were installed with 5/16-width pins.
The project also included installation of telephones and cameras for security. Because of the bridge’s height, there’s a perceived risk of “jumpers,” which required installation of assistance to those who might go to the bridge and decide they need help. All Bright Electric installed mental health assistance telephones with some state-of-the-art enhancements. The telephones are hands-free, and the company installed high-volume speakers mounted above the phone that will continue to operate should someone call and walk away.
All Bright Electric also installed high dual-focusing cameras furnished by AFA Protective Systems, which can be used by mental health professionals to see and record the activities of a person in distress, while calling for on-site professional law enforcement help.
In addition, the 20 cameras provide full-time security that is always recording and monitored by park officials. All Bright Electric installed the cameras with Category 6 cable. Johanneman said All Bright Electric persuaded the project managers to upgrade the cameras with dual focal length, so that an image could be captured whether an individual was close to the camera or far away. The company also installed outlets along the bridge’s length to accommodate events on the bridge.
Because a great extent of the work was installed on the outside of the rails, hundreds of feet above the Hudson River, the company had to take extreme safety precautions. Each individual was secured in the articulated lift when he worked, and occasionally work was suspended in hazardous weather, such as freezing rain. The project was completed without any injuries.
Most of the work took place over one of New York’s harshest winters in recent history.
“The environment was something that had to be overcome,” Johanneman said.
The work was done in wind and snow, always under the oversight of All Bright Electric’s general foreman, Sisto Braglia, who directed the project through the severe winter weather to meet the deadlines for the park opening.
With the work completed, the walkway is now open during the day and some evenings for the thousands of visitors who come to stroll, jog or peddle their way across the Hudson and to enjoy the bridge’s spectacular height.
“The walkway is a very interesting place to visit. It’s safe and [has] a park-like atmosphere,” Johanneman said.
The completed walkway also includes educational signage about the original bridge, the statistics on the walkway and the aquatic life below, and trivia about the Hudson River. Picnic areas on both sides make it a really great destination for local day trips. Weddings have already been held on the bridge’s expanse.
“But most interesting of all is that impressive 6,800-foot-long LED string of lights in view from a distance at dusk and into the evening,” he said. “All Bright Electric is really proud of this project.”
“You can’t get this kind of thing done without a responsive group,” Duffy said. “As a partnership, a lot of this was based on trust, with a public-private partnership.”