In one capacity or another, corrugated plastic pipe has been used under Interstate highways for more than 30 years. For much of that time, engineers considered it a niche alternative to the more conventional concrete and steel, recognizing plastic’s low-cost advantages, but only spec’ing it in when conditions weren’t too demanding.
Today, though, thanks to a steady engineering evolution, particularly in HDPE and HDPP materials and pipe design, corrugated plastic pipe has risen to meet or exceed the linchpin AASHTO and ASTM standards that define department of transportation applications—with some state Department of Transportations from New York to Ohio to California now allowing plastic pipe diameters of 48 to even 60 inches.
Aging Infrastructure Is Opening the Field of Competition
Reports of decades-old infrastructure systems reaching the end of their service life are extensive, and the key elements of transportation, including stormwater management, are no exception inspiring states across the country to usher in a large-scale era of infrastructure rehabilitation.
Federal funding programs like 2021’s Infrastructure Investment and Jobs Act are moving to accelerate replacement cycles, while they’re also encouraging the use of modern materials that can challenge the aging corrugated steel and reinforced concrete systems that are failing.
As a result, plastic pipe is getting a renewed opportunity to prove itself, earning a growing share of municipal and state drainage upgrades in the U.S. for a number of attributes that uniquely align with current industry trends.
Crossing the Performance Threshold
Lower material costs, lighter weight that cuts shipping expense and faster installs that have contractors reporting labor efficiency improvements approaching 40% are all advantages that have long made plastic pipe attractive to DOT officials trying to stretch budget-allocation dollars.
What’s changed so dramatically with pipe-engineering improvements is how plastic is equaling or outperforming its material competitors in a number of ways.
Unlike extremely rigid materials, corrugated plastic pipe distributes loads through soil interaction and is more resilient to ground movement caused by freeze-thaw cycles, flooding or soil instability—all factors known to cause cracks, joint separation and, ultimately, catastrophic failure in legacy steel and concrete systems.
Additionally, plastic pipe is highly resistant to corrosion, a major cause of failure in metal culverts. Studies indicate that a large percentage of pipeline failures in traditional systems are linked to corrosion, a problem essentially eliminated with HDPE. For DOTs, this means fewer emergency repairs, lower maintenance budgets and more predictable asset management.
Finally, with more frequent and intense rainfall events in many regions, plastic pipe is getting attention for its dual-wall design, featuring a corrugated exterior for strength and a smooth interior for optimum hydraulic flow. Not only does this dual-wall feature move water faster, but it creates the force necessary to propel sediment down the line, further reducing maintenance.
Presenting Unique Application Solutions
With HDPE pipe establishing itself in the DOT mainstream, engineers are also finding new and advanced ways to use it.
Trenchless Relining of Failing Culverts
Instead of replacing deteriorated metal or concrete culverts via expensive, disruptive, open-cut excavation, DOTs are using smaller diameter corrugated plastic pipe as a “slip-liner” inserted into the existing pipe. The annulus (space) between the old and new pipe is filled with grout, restoring structural integrity and extending the culvert’s life by decades.
Rapid Installation for Stormwater Management
Due to its light weight and ease of handling, corrugated plastic pipe allows for quick installation in time-sensitive roadway projects. Meanwhile, its flexibility serves extremely well in constricted areas where rigid pipe would require massive excavation.
Water Quality Polishing and Retention
Beyond just conveying water, perforated corrugated plastic pipe is often preferred in storm management as part of a filtration system to collect groundwater and reduce erosion in road embankments.
Clearing an Exciting New Hurdle in Minnesota
Engineering cost out of DOT projects is a box that never really gets checked as “done.” And that’s perhaps the one reality that most significantly expands plastic pipe’s potential.
Until 2018, only plastic pipe made of virgin resin was cleared for use in DOT applications. Since then, changes in AASHTO and ASTM standards allow for pipe made of recycled plastics, which can further reduce project
costs substantially.
Want to learn more about Fratco’s quality resin and how it’s used in our pipe? Click the thumbnail to watch a brief video!
While government adoption of such fundamental changes tends to take time, a report published by the Minnesota DOT last summer could be the tipping point that shifts use of HDPE pipe into overdrive.
There, officials used a state highway culvert replacement project as an opportunity to conduct a side-by-side test of HDPE pipe made of virgin material against that with a 40:60 virgin/recycled blend.
Three years in the ground with no discernible performance difference, the recycled-blend scored a savings of $16.4 million (7.1%) in a life-cycle cost assessment comparing “present value costs (over a 100-year period) of a 1,000-foot pipe system, (based on) materials; installation; maintenance and replacement; and anticipated service life.”
Plus, because it requires less energy to produce it, the recycled-blend pipe also scored better for its environmental benefits that MnDOT reported as “decreased impact on global warming, acidification, eutrophication (when water becomes overly enriched with nutrients) and smog”—all features sure to resonate with government transportation agencies pushing sustainability initiatives.
Set to Improve the Road Ahead
The increasing use of corrugated plastic pipe by U.S. state DOTs reflects a broader transformation in infrastructure priorities. Once focused primarily on upfront material costs, agencies are evaluating lifecycle performance, environmental impact and construction efficiency.
Corrugated HDPE pipe delivers strong advantages across all of these dimensions. It is lighter, more cost-effective, corrosion-resistant and easier to install than traditional materials, while also supporting sustainability goals and improved water management.
As infrastructure investment continues and standards evolve, the role of corrugated plastic pipe in road construction is likely to expand even further. What was once an alternative material is rapidly becoming a default choice for modern transportation systems.
FUENTES: Plastic Pipe Institute | Texas Tech Transportation Research Report | Global X | Global Growth Insights | Recycling Today | Minnesota Transportation Research
