How the Asphalt Industry Can Improve Pavement Longevity
Over the years, the asphalt industry has been working hard to improve the longevity of […]
Over the years, the asphalt industry has been working hard to improve the longevity of the pavements we drive on. We have acknowledged the fact that the right treatment, on the right pavement, at the right time is much more cost-effective than removing and replacing an asset once it’s beyond repair. We as an industry know this, the smart asset owners know this, and yet many pavements are left to deteriorate while new roads and other needs take priority.
“Asset owners have more pavements in need of preservation than money to preserve them,” John Hickey, executive director at the Asphalt Pavement Association of Oregon said. “Managers set short-term budgets in almost every sector – and that has permeated the public infrastructure sector even though the considerations driving how we budget for infrastructure necessitate a long-term perspective. Even if pavement preservation budgets initially are sufficient, funding often gets diverted to what is perceived as more pressing needs. Maybe it’s a new pedestrian bridge or light rail system – regardless of the benefit those new assets may confer, they are often paid for out of existing infrastructure funding without consideration for the long-term effects on the overall system. We tell our kids they can’t get new things until they learn to take care of what they have, but we don’t live by that rule when it comes to public infrastructure.”
And the problem isn’t getting any better. U.S. roads received a D grade in ASCE’s 2021 Report Card, retaining the D they got back in 2017. Breaking down the nation’s roads into four grading categories, 41.9 percent are categorized as “good,” 15.6 percent as “fair,” 22.6 percent as “mediocre” and 20.1 percent as “poor.”
So why has there been no improvement? The simple answer is perception.
“Pavements show deterioration relatively slowly and it is easy to think they will last another season or two, which will give us time to figure out a funding,” Hickey says. “The obvious problem is that the newly added infrastructure often costs more than we initially estimate and it also requires preservation and maintenance. Pavement managers are in a constant battle advocating for pavement preservation funding in a system where the people who allocate the dollars want to show constituents something shiny and new.”
In order to make impactful change on the lifespan of our pavements, the industry needs to continually push a long-term preservation strategy and deploy a “fix it first” mentality when it comes to our roadways.
Fix It First
According to the National Center for Pavement Preservation, there are nearly 4 million miles of paved public roads in the United States, valued at $1.75 trillion. The roads and other pavements in America are a huge investment and are vital for moving people and goods in an efficient manner. Yet we let them fall into a state of disrepair.
Unfortunately, there is very little new funding in the Infrastructure Investment & Jobs Act (IIJA) specifically dedicated to repair and no new requirements on highway monies for prioritizing repair on roads and bridges. Overall the law doubled down on the practice of giving states immense flexibility with the bulk of their money and then hoping that they use that flexibility to prioritize repair.
States should consider a “fix it first” approach to using these funds.
“In 2017, the Oregon Legislature passed a major infrastructure funding bill that had multiple funding mechanisms to adequately pay for, among other things, improving bridge seismic resiliency and preserving pavements,” Hickey says. “But, the final bill included earmark projects in primarily urban areas, which are notorious for taking a long time and being expensive.”
As inflation continues to be a challenge for State DOTs, it they truly want to do more with less money, preservation is the answer.
Finding Lasting Solutions Despite Rising Costs
If inflation wasn’t bad enough, as pavement conditions decline, pavement preservation costs increase. So what are the solutions to keep up with continual pavement decline?
In Oregon, it’s Thinlays.
“Thinlays are the most beneficial pavement preservation technique,” Hickey says. “Added structure and improved smoothness are probably the two Thinlay benefits that are most relevant since we need pavements to support increased loading and improved smoothness can result in a significant reduction in greenhouse gas emissions from vehicles.”
Thin asphalt overlays are a reliable way to restore smoothness and drivability to an aging pavement, while correcting distresses and even adding structural value in some instances. Typically, a thin asphalt overlay is a surface mix of 1.5 inches or less placed on a well prepared surface. The pavement being overlaid may be milled or unmilled, but it should not show signs of structural distress requiring a more extensive rehabilitation.
The decision to apply a thin overlay to an existing pavement surface should be made only after a careful evaluation of the pavement condition and the elimination of the need to perform a structural rehabilitation. You also need careful consideration of an entire pavement maintenance program, otherwise costs can creep up on you.
“The primary challenge in implementing a Thinlay pavement preservation program is the fact that they often have a higher initial cost and it is hard for pavement managers to overcome the budgeting hurdles described above,” Hickey says. “Marion County in Oregon is an example of an agency that has had success implementing a Thinlay program, which has improved pavement conditions and set the County up for lower pavement preservation costs over the long-term.”
Perpetual Pavements – One Inch at a Time
Perpetual pavements are designed to develop distresses from the top-down, rather than from the bottom-up. This preserves the integrity of the bottom layers of the pavement structure, and confines damage to the top layer where it can be easily managed without requiring full-depth repairs or major rehabilitation. In fact, we now know that asphalt pavements can be designed to never develop bottom-up fatigue-related distress, regardless of how many loads are applied to the pavement, and how heavy those loads may be.
By confining damage to the top layer of the pavement, maintenance and rehabilitation costs over the life of a perpetual pavement are significantly reduced. And given the fact that the lower layers of pavement are preserved, the structural life of a perpetual pavement is on the order of 50 years or more, rather than the 20-year life expectancy that has traditionally been the standard.
The cost savings and increased life expectancy are huge benefits that smaller agencies and local governments can’t afford to ignore. Both high-volume highways and interstates and low-volume county roads and city streets can reap the benefits of perpetual pavement too, even if those structures were not originally designed or built to perpetual specifications. Perpetual pavement can, in fact, be achieved by increasing pavement thickness “one inch of asphalt at a time.”
For local agencies with limited budgets, that extra inch of asphalt will pay for itself many times over by reducing long-term maintenance costs and doubling the life expectancy of the road itself.
