The asphalt in New York City is turning green
Since fights over sustainable streets usually involve bike lanes, pedestrian plazas and traffic initiatives like congestion pricing, you may be surprised to learn that the city's pothole-strewn black roads are one of New York's greenest components. That's because over the last fiscal year, the city Department of Transportation ripped 300,000 tons of potholed or damaged asphalt off the ground, carted it to city-run facilities and reconstituted it back into usable pavement, effectively recycling the city's roads.
This practice, inevitably, has given rise to its own controversy.
At a City Council transportation meeting last week, committee chair James Vacca said, “Many have raised concerns that the increase of potholes around our city is linked to the use of recycled asphalt, even though the federal studies have shown that recycled asphalt is just as good as new.”
Vacca, a Democrat from the Bronx, was talking about a not-so-recent effort by the city Department of Transportation to use more recycled asphalt pavement, or RAP, when resurfacing roads.
Even though New York City is the country's biggest road recycler, some critics, like Councilman James Oddo, Republican of Staten Island, fear that water can easily permeate RAP pavement and break it down over time. Oddo said he was sharing concerns he had been hearing from regional asphalt contractors.
“Basically, as best as I can understand it, they tell me we’ll press it, we’ll put it down, it will look great, it will pass the initial tests that the agency will do for the week or month," he said to D.O.T officials during the hearing. "But long-term it will not have the same longevity and durability as other types of asphalt.”
Deputy transportation commissioner Galileo Orlando responded: “We believe that RAP has a place in this industry.”
With 6,300 miles of roads matched with increasing oil prices, new road technologies are necessary to keep costs down. Recycling more pavement has been a D.O.T. goal for decades, but in recent years it's been linked to the sustainability framework in the Bloomberg administration's PlaNYC guidelines, making it an environmental issue rather than just a matter of cost-efficiency.
Last December, Mayor Michael Bloomberg signed a bill committing the city to make most city pavement contain at least 30 percent RAP by 2015 and for the D.O.T. to "encourage the greatest use of reclaimed asphalt pavement possible.”
(Three councilmembers voted against the bill, including Oddo.)
The pavement typically used in New York is cluster of rocks, finely crushed stones or sands and the glue-like asphalt cement binder. (Or, as city law defines it: “a dark brown to black bitumen pitch that melts readily and which appears in nature in asphalt beds or is produced as a by-product of the petroleum industry.”)
When old roads are torn up during milling, the D.O.T. brings the pavement to facilities like Brooklyn’s Hamilton Avenue plant, which processes 500,000 tons of asphalt a year. There, RAP is recycled and mixed with fresh asphalt. At the moment, that plant makes asphalt made up of 40 percent RAP; with a planned upgrade, the asphalt will be 50 percent RAP.
(Last summer, the D.O.T. Tumblr, The Daily Pothole, featured a multi-part tour of the plant, guided by Warmy, a personified chunk of pavement.)
And after a recent city acquisition of a plant in Willets Point, combined with experimentation with "warm mix" asphalts that can be spread in cooler temperatures, the Queens plant is expected to create 60-percent recycled asphalts.
Hussain Bahia, a professor at the University of Wisconsin’s Modified Asphalt Research Center, said there’s no scientific reason to avoid recycling asphalt. As he put it, it's that education hasn’t caught up with improved technology.
“It's education with producers, as well as education with the public,” Bahia said. “Look, this is a very different material and you can recycle it just like a plastic bottle. You can melt it and reshape it."
Bahia has 21 years of experience working as a pavement pioneer and spearheading research into new paving methods that involve polymers and have names like Superpave. He pointed out that in recent years, producers have found ways to improve the bonds between binder, “the black sticky stuff,” and the rocks in between, leaving less room for water to infiltrate the bonds between the rocks and the binder.
"So really it's not a complex issue,” he said. “You have glue and you have rock, and we've improved the glue, we've improved the adhesive between the glue and the rock, and we've improved the selection of the rock to make it strong."
But one barrier is making sure the previous materials are as durable as new ones, which requires safeguards.
"Now, New York is moving to 30 percent and I can guarantee you that the [D.O.T.] will put more restrictions on how to reformulate any recycled mix,” he said. “And that is needed, because they don't want people to arbitrarily just bring in rock or recycled asphalt and put it with the new mixes. You have to do the right analysis to make the new material better than the old.”
Recycling asphalt is going to be more important as the price of crude oil, a crucial component in asphalt tar, rises. Bahia said over the last five to six years, rising prices meant asphalt binder more than tripled from $200 to more $600 per ton.
But if education hasn’t caught up to technology, government investment in research and infrastructure lagging behind everything, as road traffic keeps growing.
"If you look at, say, the other industries like the medical business and the other fields, R&D in this country is anywhere between three and five percent. It's a fraction, particularly, for road construction."
He pointed out that government research is much less, about a quarter of one percent.
“I mean, it's sad how much we depend on roads, and how much little we are investing in innovation and research,” he said. “And that needs to be changed. There is no need to throw [away] these recycled materials because there's science behind it.”
Margaret Cervarich, a public affairs and marketing executive at the Maryland-based National Asphalt Pavement Association, a national trade association with over 1,200 private companies and suppliers, agreed with the positive outlook for RAP.
“They’ve done a tremendous amount of research and they’ve found that recycled mixes can be as good as, but sometimes better than, mixes with all virgin materials," Cervarich said. "Nobody has yet identified a point at which you can’t keep recycling the materials. As far as we know, you can recycle and reuse it over and over again indefinitely."
Even though 100 million tons of recycled asphalt are reused each year, according to the most recent figures in a Federal Highway Administration Report, only 12 percent of the country's roads use RAP. In some other counties, like Japan, the percentage is much higher.
“In Japan, they just don’t do things, they invest a lot more in infrastructure than we do," said Cervarich. "They are not going to put down asphalt mixes that aren’t high quality. And yet, they figured out a way to do 50 percent recycled content.”
She said some of the resistance in America came from contractors and private suppliers who want to stick with “really, really, really proven science.”
“I mean what they’re doing is basically building something that basically has to last for X number of years, lets say 30 years,” she said. “And they want it to be right. They’re good public servants, they’re trying to do the right thing and if they have a procedure that’s been working for them for ten years or 20 years, they want to stick with that. They don’t want to make changes that could potentially have a bad outcome. Sometimes people are just so conservative, and I don’t mean that in a political way, but more of an emotional way, where it’s hard for them to make a change. They just prefer to do it the way they’ve always done it.”
Cervarich said she was excited by the potential of recycled asphalt. And she sounded like she meant it.
“Between 2009 and 2010, we saved three million tons of asphalt binder, which translates to 19 million barrels of asphalt cement,” she said. “That’s a big number. That is really an awesome number.”