FRP pedestrian bridges gain a foothold in the marketplace, offering innovative designs and lightweight solutions.
On opening day of New Zealand’s Auckland Harbor Bridge in 1959, locals walked across the eight-lane motorway bridge. Since then, the 3,348-foot long bridge has been reserved for vehicles. But in late 2015, people will crisscross the harbor on foot once again with the opening of SkyPath, a pedestrian bridge that will be attached to the existing steel vehicle bridge.
Still in the design phase, the SkyPath project involves several companies, including Gurit, Core Builders Composites and Aireys Consultants. The bridge will use more than 4,000 square meters of sandwich panel decking composed of fiberglass-reinforced foam core with e-glass and epoxy resin skins. Each section of decking will be equipped with beams and ribs of carbon fiber and fiberglass unidirectional reinforcements and epoxy resin. When completed, SkyPath will be semi-enclosed with a mesh fabric to provide air flow yet ensure the safety of pedestrians.
“While we’ve had to go through a significant design update and testing program, we have now achieved a composite solution for a similar price to steel and aluminum construction,” says Bevan Woodward, project director of the Auckland Harbor Bridge SkyPath Trust. “This means SkyPath will be stronger and lighter, will be easier to implement and have much lower maintenance costs with a service life of at least 50 years.”
With a growing interest in the recreational trail movement, increased attention on multi-modal transportation and more applications in urban and industrial settings, demand for FRP pedestrian bridges such as SkyPath is on the rise. Another factor in the momentum shift is the increasing acceptance of FRP building materials on the part of influential players such as the Federal Highway Administration (FHWA) and American Association of State Highway and Transportation Officials (AASHTO). These organizations have championed FRP through technology transfer programming at industry conferences and the publication of guides and regulations. While acceptance has been slow, the tide may be turning, according to Scott Reeve, president of Composite Advantage, a Dayton, Ohio-based manufacturer of FRP bridge decks and other structural composites.
To date, the 2008 “Guide Specifications for Design of FRP Pedestrian Bridges,” published by AASHTO and developed in part by ACMA’s Transportation Structures Council, is the industry’s primary reference. In 2011, the U.S. Department of Transportation (DOT), FHWA and the U.S. Forest Service reissued their “Guide to Fiber-reinforced Polymer Trail Bridges.”
“The development of codes and standards and their expansion will support the growth of pedestrian bridges,” says Dustin Troutman, director of marketing and product development for Creative Pultrusions Inc., a manufacturer of FRP bridge decks and custom structural profiles in Alum Bank, Pa. “These standards enable cities, counties and park management entities to more easily incorporate pedestrian bridges into their environment. They are a catalyst for the future of this industry.”