WEST NYACK, N.Y. — McLaren Engineering is part of a team named in R&D Magazine’s “Top 100 Innovations” for its work in developing the world’s first high-load all thermoplastic composite bridge to support heavy vehicular traffic. The team of McLaren, U.S. Army Engineer Research and Development Center, Rutgers University (Dept. of Materials Science and Engineering), and Axion International worked together to create an all thermoplastic composite (ATC) bridge design which would be cost-competitive with wood or other bridge materials and support the required DOT regulations for vehicular traffic.
The team’s eco-friendly all thermoplastic composite bridge uses an innovative resource-efficient I-beam design and patented mixture of composite material that reduces the amount of material used in each beam without compromising its structural integrity. The design was used in a bridge installed in 2009 at the U.S. Army base in Fort Bragg, N.C., and surpassed tests by easily supporting a 70-ton fully equipped M-1 Army tank and showing a wheeled vehicle limit of 88 tons.
Malcolm McLaren, president and CEO of McLaren Engineering, said the team has been developing and testing all thermoplastic composite bridge designs for nearly a decade, but the breakthrough which won the team R&D Magazine’s Top 100 Innovations is that the material and design has reached the cost-competitive level.
“Our ability to successfully meet the 88-ton load level and equalizing or better wood costs means more commercial applications in short-span bridges and other high-capacity load structures beyond use on military bases,” said McLaren. “Thermoplastic composite, better known as plastic lumber, is not a new concept. Among other items it has been used in picnic tables, decking and in lesser load-bearing structures such as foot bridges and lightweight vehicle bridges. But before our team’s work it was unheard of for high-capacity load structures. We trust that this recognition by R&D Magazine and our success with the Fort Bragg bridge will make plastic lumber no longer just a novelty championed by environmentalists but a viable choice for serious consideration by the construction industry for high-capacity load structures such as large decks, docks, seawalls, wharves and railroad bridges.”
The world’s first suspension bridge using thermoplastic composite is a 31,000-pound capacity single-lane bridge in New Baltimore, N.Y., near Albany, and has shown no signs of deterioration since being built in 2000. The Fort Bragg ATC bridge consists of 94 percent recycled materials including glass, vehicle bumpers and some 85,000 pounds of high-density polyethylene plastic — the equivalent of roughly 550,000 one-gallon plastic milk jugs. Innovative plastic I-beam components were used to support the heavy loads, and to provide a design that is cost-competitive to standard treated-wood bridges designed to carry the same load.
There are a number of advantages of all thermoplastic composite bridges over timber bridges. ATC rarely cracks or splinters. It also resists rot, mildew and termites, is weather- and graffiti-resistant, and is not affected by bacteria, worms, insects or rodents. ATC provides a good shock-absorbing surface for pedestrian traffic, requires no waterproofing, staining or regular maintenance, and is aesthetically pleasing. It can be manufactured to meet different design and appearance specifications. The structure also has a life expectancy of 50 years — twice as long as a treated-timber bridge.
Moreover, ATC is eco-friendly and when used in high-capacity load structures such as short-span bridges results in larger amounts of plastics removed from landfills and fewer trees cut for lumber.
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