Feb 19, 2021
South Jersey’s Wharton State Forest is home to a unique bridge constructed from a renewable resource—thermoplastics. A team of Rutgers University researchers developed a unique formula to transform discarded plastic bottles and foam containers into a strong and durable construction material. This 100% recycled plastic material is lighter than wood or concrete and is projected to far outlast traditional construction materials. With a weight capacity of 36 tons, this bridge can easily sustain the weight of cars, trucks, and heavy forest fire service equipment crossing the Mullica River, which provides critical access to the Goshen Pond section of Wharton State Forest west (upstream) of Atsion Lake.
Rutgers Professors Thomas Nosker and Richard Renfree, along with their team of graduate students, developed the bridge’s thermoplastic composite material, a carefully combined mix of high-density polyethylene (HDPE) and polystyrene (PS). HDPE is the type of plastic typically marked with the number “2” inside of a recycling symbol. It is found in stiff plastic, like milk bottles, liquid containers, and laundry detergent bottles. PS, indicated with the number “6,” is used to create foam products like coffee cups, egg cartons, and clam-shell takeout containers. Polystyrene has increasingly become harder to recycle in curbside collection programs nation-wide.
This team of researchers and developers were joined by students and volunteers to construct this bridge in 2002, replacing an older wooden bridge that was destroyed by fire. Although other thermoplastic bridges were constructed in the United States around the same time, this was the first bridge to have its load-bearing I-beam substructure entirely molded from plastic. A bridge’s I-beam must be carefully engineered to bear and distribute applied weight. It must have the right proportion of flexibility and durability, something this recycled plastic material was able to provide.
The bridge is also resistant to rot, mold, and fire. Its lightweight nature facilitates quick and easy installation without the use of heavy machinery, too. Thermoplastic bridge pieces were molded and designed to nest together, adding an easy reinforcement to strengthen the entire structure. The bridge has a long-life expectancy and although some routine repairs may be needed, they are projected to be inexpensive and infrequent.
This nearly two-decade old bridge nestled in the Pine Barrens has proven to be a successful demonstration project for recycling in action. Recycling makes a difference. Developing a beneficial reuse for recycled products demonstrates the true value of community recycling programs, showing that curbside recyclables put out at the street can be transformed into something useful. However quirky, this bridge serves as a reminder for the potential of what can be done with materials that would otherwise end up in a landfill.
Learn more about this bridge:
World's First Thermoplastic Bridges
Recycled Plastic Lumber Invented by Pioneering Rutgers Professor - Rutgers Today
Learn more about Rutgers Professor Thomas Nosker
See how Atlantic County’s recycling gets transformed:
#1 PET bottles become:
-other plastic bottles, soft drink bottles, honey, liquor, dish detergent bottles, toiletries, recording tape, food packing, heatable food trays, and carpet fiber.
#2 HDPE jugs become:
-other juice, milk, and water containers, rubbing alcohol bottles, laundry detergent bottles, dispensers, dental floss, baby wipes, motor oil bottles, and antifreeze containers.