Pipe tested under commuter rail lines in Pennsylvania
Researchers at Villanova University completed a study of the performance of corrugated, high-density polyethylene (HDPE) pipe containing recycled HDPE resin in commuter rail installations, finding its performance to be indistinguishable from pipe made from virgin material.
The three-year field and laboratory evaluation is an important step in validating the use of corrugated HDPE pipe manufactured with recycled materials for commuter railroad and highway applications. The study was funded cooperatively by the Southeastern Pennsylvania Transit Authority (SEPTA) and the National Cooperative Highway Research Program (NCHRP) Project 4-39.
“The railroad industry is reliant on drainage infrastructure materials that are sustainable and resilient and offer a long service life relative to the cyclical live loading conditions typical in these applications,” said study-author Michael Pluimer, a pipe industry authority and Ph.D. graduate from Villanova. “Since pipes manufactured with recycled materials can be more sustainable and cost-effective than those manufactured with 100% virgin materials, it was important to compare the performance and durability of the pipes in these applications.”
In the study that began in October 2013, two 30-in. diameter corrugated HDPE pipes (manufactured by Advanced Drainage Systems Inc.)—one made with 100% virgin materials and one with 49% post-consumer recycled content—were installed underneath a SEPTA main commuter rail line near Doylestown, Pa., some 25 miles north of Philadelphia. Approximately 36 trains passed over the pipes daily for three years, after which a detailed analysis showed both pipes to be performing as designed with no noticeable differences between the two pipes. Measured strains and deflections on both pipes were found to be minimal and well below industry recommendations. Based on the field measurements, a laboratory test was developed to assess the long-term performance of the pipes relative to fatigue and stress cracking via the slow crack growth (SCG) mechanism.
Based on this testing, it was determined that both pipes—the one manufactured with virgin materials as well as the one with recycled materials—should have a service life in excess of 100 years.
“The transportation industry, just like many other areas, is seeking to incorporate more sustainable and cost-effective engineering materials and practices into their infrastructure systems,” said Tony Radoszewski, CAE, president of the Plastics Pipe Institute. “This has prompted research into new products that can be manufactured with more sustainable materials, such as those incorporating recycled content. The incorporation of recycled materials into products used in transportation infrastructure offers both economic and environmental benefits.”
Evaluation of the Long-Term Performance of Corrugated HDPE Pipes Manufactured with Recycled Materials for Commuter Railroad Applications by Michael Pluimer is available free of charge.