Performance under heavy loads

February 2013 » Features » PROJECT CASE STUDY
Tests advance use of corrugated HDPE pipe for rail terminal stormwater drainage.
Norfolk Southern's $2.5 billion Crescent Corridor initiative is establishing an efficient, high-capacity, 2,500-mile intermodal freight rail route between New Jersey and Louisiana.
Photo: Norfolk Southern Corporation

Spanning 380 acres, the Norfolk Southern Memphis Regional Intermodal Facility rail-to-truck terminal that opened on July 1, 2012, in Rossville, Tenn., is projected to handle more than 327,000 truck trailers and containers a year, with four trains arriving and departing daily, offloading cargo. The facility is part of the multi-state $2.5 billion Crescent Corridor initiative to establish an efficient, high-capacity, 2,500-mile intermodal freight rail route between New Jersey and Louisiana on Norfolk Southern's rail network.

Project
Norfolk Southern Memphis Regional Intermodal Facility stormwater system

Product application
Advanced Drainage Systems Inc. corrugated high-density polyethylene pipe used for stormwater system beneath heavy freight trains at intermodal shipping hub.

An intermodal facility is a rail terminal for transferring freight from one transportation mode to another – trains to trucks – without handling the freight itself. Because of its strategic location, the Memphis facility makes intermodal freight transportation more truck competitive between the South and major Northeast markets.

The pivotal part of the entire facility's design was to get the ground as flat as possible, giving locomotives a level run of track, which means less power to start rolling. The location where the facility now sits was an area comprised largely of woods that was excavated down to approximately 25 feet below grade to establish a level surface.

The site's stormwater drainage system used 36,216 feet of corrugated high-density polyethylene (HDPE) pipe that ranged from 6 inches to 60 inches in diameter. Another 5,700 feet of perforated corrugated HDPE pipe was used to allow water to seep into the pipe. Burial depths under parking lots and train tracks ranged from 2.5 feet to 28 feet from the bottom of the railroad tie to the top of pipe.

The American Railway Engineering and Maintenance-of-Way Association (AREMA) recently approved corrugated HDPE pipe for such use. The new facility is to be heavily traveled and the underground pipe system will be subjected to hundreds of tons of weight from anticipated rail traffic. For the $129 million project, the use of HDPE pipe also ensures the water drainage system is in compliance with state and federal water quality regulations.

Historically, the railroad had specified heavy gage, riveted, annular corrugated metal pipe with a bituminous coating, or reinforced concrete pipe. However, new focus on the benefits of using corrugated HDPE pipe, including corrosion resistance, cost of construction, and structural capacity under Cooper E80 Loading conditions, led to its selection for the Norfolk Southern facility.

AREMA's approval of corrugated HDPE pipe in railroad applications was published in the AREMA design manual in April 2012. Additional data supporting the pipe's use also came from a Plastics Pipe Institute Inc. (PPI)-sponsored industry study that yielded results showing optimal performance in long-term use of corrugated HDPE pipe under railroad systems.

The PPI-sponsored research evaluated the use of corrugated HDPE pipe for under heavy rail car loads with shallow cover. Testing and data collection was conducted by the Transportation Technology Center Inc. at the Facility for Accelerated Service Testing (FAST; www.aar.com/tracks.php) in Pueblo, Colo., where it operates a test bed for railroad track. The methodology for analysis involved repeatedly running a train consisting of four locomotives with eighty, 315,000-pound rail cars over 48-inch corrugated HDPE pipe with only 4 feet of cover from the top of the pipe to the bottom of the rail.

Twenty-foot sections of ADS N-12, 48-inch diameter AASHTO M294 Type S, pipe are ready to be installed at the Norfolk Southern Memphis Regional Intermodal Facility.

In addition to the dynamic performance evaluation, the long-term impact of heavy, static loads on the pipe was assessed by parking rail cars with one set of wheels on the track directly over the same pipe for six weeks. Advanced Drainage Systems Inc. (ADS) manufactured the corrugated HDPE pipe used for both the test and the new Norfolk Southern facility.

Burial depths of corrugated HDPE pipe under parking lots and train tracks ranged from 2.5 feet to 28 feet from the bottom of the railroad tie to the top of pipe.

According to ADS design engineer, Shawn Coombes, P.E., "For our 48-inch-diameter pipe we require at least 4 feet of cover for Cooper E80 Loading. In one 80-foot section [of the intermodal facility], however, there could be only about 2.5 feet of cover, so we did a custom design to modify the backfill to allow it to perform under those conditions. That was the only real challenge we had."

"The Memphis Norfolk Southern Intermodal Facility is the culmination of more than five years of effort working with AREMA and the railroad community to advance the use of HDPE pipe into railroad's heavy haul operations, where proven performance under Cooper E80 Loading is required," said Tony Radoszewski, executive director of the PPI. "The Memphis project also reflects the railroad community's acceptance of PPI's efforts to initiate under-track testing at Transportation Technology Center's FAST. This groundbreaking work with HDPE pipe was done at a time that matched the railroads' explosive growth, proving to be both timely and beneficial."

The Norfolk Southern Memphis Regional Intermodal Facility project was named the Project of the Year by the PPI. The award was presented to ADS at the PPI's annual 2012 meeting.

This article was contributed by the Plastics Pipe Institute Inc. (PPI; www.plasticpipe.org), a trade association representing all segments of the plastic pipe industry. PPI provides technical, engineering, and industry knowledge resources for use in development and design of plastic pipe systems. Additionally, PPI collaborates with industry organizations that set standards for manufacturing practices and installation method.including health care, commercial, institutional, federal, municipal, industrial, and wastewater treatment.

Upcoming Events

See All Upcoming Events