Every day, thousands of commuters on Miami’s rapid transit system are whisked to work cushioned by a bed of empty milk jugs, discarded laundry detergent jugs and other household castoffs.
The plastic in question isn’t the familiar debris that accumulates in rail tracks, along roadways and on the sidewalk. Rather, the trains’ journeys are smoothed by super-rugged railroad ties made up of veritable mountains of plastic waste recycled from consumers’ trash.
At a quick glance, the dark plastic ties are tricky to distinguish from the heavy wooden beams they replace. Their performance is vastly different, however.
Where conventional wooden ties degrade, sometimes in just a few years, the recycled plastic composite ties do not.
In fact, the material “is basically impervious,” says Steve Silverman, president and chief executive of New Jersey-based Axion International Holdings, which supplied its Ecotrax composite ties to Miami-Dade Transit.
“It doesn’t rot. It doesn’t corrode. It doesn’t absorb water. Bugs don’t eat it,” he adds.
Silverman estimates the longevity of the plastic ties to be at least 40 years, compared with a few years for wooden ties in harsh environments. What’s more, it needs no maintenance, such as painting or re-sealing.
On a run of heavily used Long Island Rail Road commuter rails, a batch of Axion ties in service over the past eight years showed no signs of material degradation, according to a recent independent lab study.
If anything, the ties’ performance had improved slightly. As the plastic weathered, it hardened slightly, tightening its grip on the spikes, screws and hardware that attach the rails to the ties.
More than 150,000 of Axion’s ties can be found in rail beds on six continents. The company is also pushing into the construction industry, where its composite I-beams, planks and structural members are being used to rebuild bridges formerly made of wood, concrete or steel.
If Axion’s approach takes off, the environment may prove to be the biggest winner.
Using recycled composites in these heavy-duty applications has the potential to usefully absorb enormous flows of plastic waste. Today, just 8 per cent of plastic is recaptured, according to the U.S. Environmental Protection Agency. More troublesome still, a significant share of waste plastic is lost to the environment.
Because plastic waste does not degrade it does cumulative harm to the environment, whether in your backyard or floating far out in a Pacific Ocean gyre.
On land and on water, loose plastic waste often ensnares wildlife. It has also begun to penetrate natural food chains. As it breaks up into microscopic bits, plastic debris is consumed by tiny creatures, which are in turn eaten by bigger fish or birds. At each step in the food chain, traces of plastic and related additives accumulate, explains Susan Freinkel in her 2011 book, Plastic: A Toxic Love Story.
Humans are tainted by plastic, too. Blood tests reveal widespread exposure to synthetic chemicals used in plastics circulating in our bodies.
Axion’s Miami project offers a glimpse at the impact that recycled composites could have in diverting the growing tide of plastic.
So far, Miami has purchased around 2,000 composite ties, made up of roughly one million pounds of recycled plastic. By comparison, every year, the U.S. rail system replaces some 20 million ties.
As a thought experiment, if all those replacement ties were made of recycled plastics, the effort could usefully sequester some 10 billion pounds of waste, more than twice the volume of all the plastic recycled in the U.S. in 2010. Besides being stable and enormously strong, the composite ties can also be recycled at the end of their life.
For now, Axion is focusing on rail and construction markets where the relatively high upfront costs of its composites pencil out by avoiding more frequent future replacements. In the U.S. and overseas this dictates a focus on regions similar to Florida, where it’s hot, wet and salty, and insects are rife – conditions where wood products are short lived.
Longer term, Silverman sees bigger opportunities using plastic garbage to help remake America’s crumbling infrastructure. A 2011 Federal Highway Administration report estimates that more than 143,000 bridges are either structurally deficient or functionally obsolete, largely due to the sort of corrosion, wear and tear to which recycled structural composites are immune.
But first the company has to drive down the cost of its raw material. Though the world is awash in plastic, too little of it is recycled.
“If the U.S. recycled more, our prices would come down,” says Silverman.
That could be a triple win: for Axion, the country’s infrastructure and the environment.
Click here to view our complete Tech Savvy series.