A Rutgers-developed structural “lumber” made from recycled plastic is once again flexing its muscle – this time in two bridges that carry freight trains over streams at the U.S. Army’s Fort Eustis installation in Newport News, Virginia.
The latest achievement on the Fort Eustis Military Railroad comes less than a year after the Army built two plastic bridges at Fort Bragg, North Carolina, to carry 70-ton Army tanks across streams on a course used for military training exercises. The railroad brought out its 80- and 120-ton diesel locomotives in April to test the bridges’ strength, then did a public demonstration on May 27 for Army brass and local media.
In both Army installations, lumber made from recycled milk and detergent bottles blended with recycled plastic automobile bumpers was used to replace rotting wooden bridges. Replacement wooden bridges would have required environmentally harmful preservatives to fight rot and insect damage along with costly routine maintenance. The other alternative – concrete or steel construction – would have been more expensive and time-consuming.
According to Tom Nosker, principal investigator with Rutgers’ Advanced Polymer Center, the 40- and 75-foot railroad bridges so impressed the Fort Eustis brass that they have put out bids for two more, each about 10 times as long.
“The next two bridges will carry the railroad over protected marshlands on the base,” said Nosker, referring to the proposed 450 and 500 foot spans. “These are ideal settings for using our durable and environmentally friendly material.”
Fort Bragg has also put out bids for two more tank bridges, both longer than the first two.
The plastic formulations for the railroad bridge materials didn’t change – they are still high-density polyethylene from milk and detergent bottles along with polypropylene and fiberglass from scrapped automobile bumpers. But the project gave Rutgers and its manufacturing licensee, Axion International, the opportunity to work with new structural designs in challenging construction situations.
“We’ve added more material to the beams to handle the heavy load of a freight train and we pre-assembled groups of beams at the factory to speed construction in the field,” said Nosker, who is affiliated with the university’s Department of Materials Science and Engineering.
He also noted a particularly tough challenge with the soft sandy soil on the base. “We had to drive some pilings down as far as 70 feet to ensure that they would support the loads.”
Their success has others looking – including a bridge engineer for one of the country’s major freight railroads. While concrete and steel railroad bridges that span highways and rivers are more visible to the public, the lowly wooden bridges that cross creeks and streams still comprise a third of the bridge inventory of the country’s major railroads, according to one industry estimate. The railroad bridge market thus looks attractive to Axion International.
Fort Eustis is the home of the U.S. Army’s Transportation Corps, which is responsible for the movement of Army personnel and material. The base’s railroad provides rail operations training for Corps personnel and is used to move materials around the base.