Swareflex Wildlife Warning Reflectors: One Preventive Measure for
Discussion of Sign Management Technologies
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Announcement and Call for Papers: Seventh International Conference on Low-Volume
Tires: A New Source for Culvert Pipe
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Tires: A New Source for Culvert Pipe
Using truck tires in the manufacture of culvert pipe reduces the need for landfill
space, eliminates a fire hazard, and deprives mosquitos of breeding sites.
Moreover, recycled-tire culverts offer an initial cost advantage over traditional pipe
materials; however, their increased weight, shorter sections, and thicker walls result
in higher installation costs. The present study of installed waste-tire culverts
determined that the pipe was working with few problems. Tests showed that
although the pipe sections themselves did not leak, joints between pipe sections
have the potential for leakage that may cause soil erosion. Future research is
needed on pipe durability, steel reinforcing bar (rebar) corrosion, and joint
Summarized here is a report by researchers J. L. Gattis and Jess W. Everett entitled
"Evaluation of Culvert Pipe Made from Waste Truck Tires." The report appeared in
the Transportation Research Board's Transportation Research Record 1541,
Structures, Culverts, and Tunnels published in 1996. This research was funded
by the Oklahoma Alliance, Center for Resource Conservation and Environmental
Research, and the Mack-Blackwell National Rural Transportation Study Center at
the University of Arkansas, through a grant from the U.S. Department of
Truck-tire pipe, used in Arkansas, Oklahoma, and Texas for surface drainage in
open channel flow conditions, had not been independently tested. Therefore, the
objectives of this research were to:
- determine how truck-tire pipe performed in the field and
- assess leakage potential.
MANUFACTURING TIRE PIPE
Heavy truck tires are often shredded before disposal, a process that may hasten the
wearing of shredding equipment. One solution to the cost of replacing shredding
equipment is the manufacture of drain pipe from waste truck tires. The process also
reduces the demand on landfill space.
Pipes are made by cutting the bead and sidewall from the tread. Eighty of the
resulting discs are stacked and compressed into a tube about eight feet long. Rebar
treated with a rust inhibitor is wrapped lengthwise and welded around the pipe.
FIGURE 1: Fabrication of truck-tire pipe: (a) 80 truck-tire beads and sidewalls stacked on from, (b) beads and
sidewalls compressed by piston to approximately 2.5 m, (c) beads and sidewalls secured by four welded rebars ste 90 degrees apart
The range of tire sizes determines the pipe diameters available. Although
cost-effective, using a waste material does not produce the uniform appearance that
the pipe might have if made from new materials.
PERFORMANCE ISSUES: FABRICATION TO INSTALLATION
The researchers compared truck-tire pipe with galvanized corrugated steel and
fiberglass pipe. Prices ranged from $5.25 to $6.00 per linear foot for either steel or
fiberglass, if purchased in large quantities. Used oil-well pipe, available in some
areas, sells for about $7.00 per linear foot. The purchase cost of truck-tire pipe,
however, is $3.00 to $5.00 less per linear foot.
Because it takes longer to install than galvanized or fiberglass pipe, installation
costs for truck-tire pipe are higher. Installation time for truck-tire pipe may be to two
to three times longer than for other pipes.
Tire Pipe Manufacturing Issues
The manufacturing process described above results in a pipe with an uneven end
because the rebars pinch the stack of tire disks. A flat end would be preferable for
joining the pipe sections. Another issue is the advisability of using thicker rebar.
Increased rebar diameter would make the pipe last longer. The manufacturer
prefers 9.5 mm rebar, because it bends more easily than larger sizes.
Shipping and Handling Issues
Truck-tire pipe is heavy; it weighs about 150 pounds per linear foot, and standard
eight-foot sections weigh 1200 pounds. Damage during transport may occur if the
pipe is dragged across other pipe sections or dropped on the end.
Installers can also damage the pipe if it is flexed laterally, so they must be careful
when placing it in a ditch. Some rebar welds have broken during installation. A
backhoe can hoist the pipe with a chain or rigid bar passed through it. Although one
county reported that the pipe was too heavy and awkward to handle, most pipes
were not damaged during preinstallation handling.
Since tire pipe is new, its installation procedures are still evolving. These installation
issues were discussed:
- site preparation procedures,
- the type of bedding, if any,
- jointing procedures,
- amount of cover needed over the pipe, and
- installation cost and time requirements.
Site Preparation Procedures
At one site crews reported that irregularities in the pipe surface required a smoother
ditch than galvanized pipe, because determining the pipe slope by looking at it in the
trench was difficult. A muddy ditch also made the pipe harder to install.
Due to its greater wall thickness, tire pipe must have a deeper trench than
thin-walled pipe with a similar inside diameter. Some road crews reported having to
raise the road surface to allow for a deep enough ditch.
Truck-tire pipes can be bedded similarly to other types of culvert. Types of bedding
reported to the researchers included:
- installing the pipe directly on the dirt surface,
- using crushed stone, and
- encasing the pipe in concrete at a low-water crossing.
Joint Connection Procedures
The short length of truck-tire pipe means it takes several sections to cross an
average roadway. Joints must be tight enough to keep surrounding water and soil
out and to keep pipe contents in. Most tire-pipe joints were wrapped with conveyor
belt or geotextile cloth strips. Some were fastened with plastic ties. One crew
welded rebar across the joints. Some crews butted the pipes together with no other
Because of the irregular pipe ends, it was difficult for installers to create snug joints.
Also, the use of chains to lower the pipe required crews to leave room between pipe
sections so they could remove the chains. One researcher suggested that installers
rotate each pipe section one-eighth turn to avoid matching up the indentations
caused by the rebar bands.
In only one situation was shallow installation a problem. The researchers suggested
that the pipe be installed with enough cover to allow for road maintenance, such as
PERFORMANCE EVALUATION: FIELD EXPERIENCE
The researchers visited 26 installation sites, mostly on country roads in rural areas
or small towns. Usually, traffic volumes were light. Most pipe installations consisted
of one or two pipe runs of three or four pipes under dirt or gravel roads.
Pipe performance criteria studied included:
Water-carrying capacity and debris-accumulation potential inside the pipe
because of the rough surface,
Erosion, especially at joints, and ability to withstand flooding,
Ability to carry the weight of vehicles passing over the pipe,
Potential for continuous and excessive flexure, causing deterioration of the
road above the pipe, or pipe movement and migration,
Failure of rebars from corrosion, resulting in pipe failure, and
Susceptibility to fire damage.
The irregular surface did not seem to create debris deposits, even after more than
two years. Sediment observed in the bottom of some culverts appeared to be
caused by the pipe flow-line being too low or by erosion upstream. In some places,
vegetation had been caught between the rebar and the pipe wall.
In the few cases where researchers observed road embankment erosion near a pipe
end, it appeared that the cause was "insufficient compaction of the backfill on the
embankment slope, and subsequent surface erosion on the side of the
embankment." Of the approximately 90 joints observed, researchers found three
cases of road-surface erosion, possibly caused by gaps at the pipe joints. It was
suggested that a wider wrap might solve this problem.
At one site, the truck-tire pipe remained when other types of pipe washed out,
perhaps due to the tire pipe's extra weight. At another site, however, the tire pipe
washed out immediately during heavy rain, but did not create any problems after
Loads and Deflection
The researchers observed two instances of pipe deflection (deformation, or deviation
from roundness). In one case, an overweight vehicle had driven over the culvert.
Improper backfilling or insufficient soil compaction might also cause these
Cover and Flexure
The pipe installations had cover depths ranging from one to two inches to more than
eight inches. Some roads showed hairline cracks at the installations, possibly
caused by crossing traffic vibrating the pipe. No problems were observed as a result
of the cracks.
At one site the rebar had given way after a culvert installation, perhaps due to an
inadequate weld. Researchers suggested that pipe failures may also result from
Although no tire pipe damage was found due to fire, the research team recognized
the potential for fire damage caused by vandals or accidents.
Leakage, either from outside or inside a pipe, can cause erosion that could result in
cave-ins. The researchers conducted tests on single sections and joints.
The single-section wall leakage test took place outside in dry weather at 80 degrees
F. with a pipe section sealed with plywood plugs nailed and caulked six inches from
the pipe ends. No leaks were observed from the pipe walls. The researchers
concluded that "leakage through the truck-tire pipe walls should not occur at
measurable rates under open channel flow conditions."
The joint-leakage test was outside in dry weather at 90 degrees F. Researchers
joined two sections of pipe with 36-inch-wide conveyor belting and cinched it with
aircraft cable to simulate a field installation. The open pipe ends were plugged with
caulked plywood as above. Water leaked from the joint as fast as it entered the
pipe, so researchers were unable to set a rate of escape. They did, however,
observe that because of the tire pipes' irregular surfaces and slightly different
outside diameters, they were unable to make a tight connection with the conveyor
belt material. They surmised that "significant leakage will occur when the pipes are
not surrounded by soil," but that "[a]t actual tire-pipe installations, the ability of
surrounding soil to act as a mud-seal around the joint could vary from site to site."
Galvanized pipes may last from 20 to 25 years, and fiberglass pipes may last 50
years. To learn the lifespan of truck-tire pipe, more research should be conducted.
Rebar corrosion and degradation of the rubber should be studied at regular intervals
over time. Joint connections should be tested under field conditions and in a variety
of soils and flow rates.
While acknowledging that resulting changes would add to manufacturing costs, the
project team suggested future research into ways to make pipe ends flat so they can
be joined more tightly. One suggestion was to make the pipe from reconstituted
rubber and construct it with formed ends. This would eliminate the need for rebar
and allow ends to be butted more closely for a more watertight seal. Also,
constructing the pipe with holes at the mid-point for attaching hoisting chains would
allow lifting from the middle rather than wrapping chain around the ends. Again, the
ends could then be laid together more tightly.
Copyright © 1997 by TranSafety, Inc.
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