Researchers at Villanova University in Philadelphia have completed a study of the performance of recycled-content corrugated, high-density polyethylene (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 was designed to help validate the use of corrugated HDPE pipe manufactured with recycled materials for both railroad and highway applications. It was funded by the Southeastern Pennsylvania Transit Authority (SEPTA) and the National Cooperative Highway Research Program (NCHRP), via its 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,” says study author Michael Pluimer, a PhD graduate from Villanova with pipe industry research experience. “Since pipes manufactured with recycled materials can be more sustainable and cost-effective than those manufactured with 100 percent virgin materials, it was important to compare the performance and durability of the pipes in these applications.”
In the study, the field portion of which concluded in 2016, two 30-inch diameter corrugated HDPE pipes manufactured by Hilliard, Ohio-based Advanced Drainage Systems Inc. (ADS) were installed underneath a SEPTA main commuter rail line near Doylestown, Pennsylvania, about 25 miles north of Philadelphia. One pipe was made with 100 percent virgin materials and the other with 49 percent post-consumer recycled content.
Approximately 36 trains passed over the pipes daily for three years, after which an analysis showed both pipes to be performing as designed with no noticeable differences between them. Based on field measurements, a laboratory test was developed to assess the long-term performance of the pipes relative to fatigue and stress cracking. Based on that testing, it was determined both pipes “should have a service life in excess of 100 years,” according to the study.
“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,” says Tony Radoszewski, president of the Irving, Texas-based Plastics Pipe Institute Inc. (PPI). “The incorporation of recycled materials into products used in transportation infrastructure offers both economic and environmental benefits.”
Comments Daniel Currence, director of engineering for the Corrugated Plastic Pipe Division of PPI, “For more than 50 years, HDPE pipe has been known to stand up to tough environments including toxic waste and high pH levels. Its projected 100-year service life has been documented by independent studies and state and federal government agencies, including departments of transportation.”
He continues, “Additionally, pipe made from HDPE can be recycled into many products including pipe, which is exactly what was used and validated in this study.”