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Springtime: The season of sunscreen, allergy meds and pavement preservation

Photo of Paul Keesler with Oro Valley Town Seal

Oro Valley residents will soon see the signs of spring: various critters will reappear seeking to bask in the sun’s glow, poppies and other flora will begin to bloom–setting off more than a few rounds of sneezing and frantic trips to procure allergy medications, and it’ll be time to stock up on sunscreen, lotion and other summer necessities. Those preventative measures for your skin also relate to another telltale sign of spring: pavement preservation.

March 22, 2019

When you drive through Oro Valley, you’ll notice contractors and public works personnel out on the roadways performing road maintenance activities. While this work may seem like an inconvenience to some, it’s also one of the reasons the Town’s roads have earned a reputation for being the best in the region. Given our traffic levels and the environmental extremes here, this is no small accomplishment.

The success of our pavement preservation has been predicated on the support of the Town Council and Town staff’s proactive approach to the process. Council has historically voted to approve funding for this important program. For the FY 19-20 budget, staff will be requesting $1.4 million to fund the next fiscal year’s round of preservation efforts. Public Works engineering personnel actively maintain a database of Oro Valley’s public roads and physically inspects them every year to keep our 10-year Pavement Preservation Plan up to date.

These annual inspections are vital. We can anticipate the damaging effects of heat, cold and precipitation on pavement. But changing traffic patterns and heavier use accelerate pavement deterioration by initiating microscopic movement within the pavement as traffic passes over it. Vehicles stopping and starting cause stress to the roads, along with turning movements. As the region grows and thrives, more commuters use our roads, and we see the effects of all of those vehicles on our pavement.

So how do we keep our pavement in good condition? Think of pavement as a layer of skin. The sun evaporates moisture out of the road and creates the same problems for pavement that it does to your skin. It causes it to weather and crack. And like skin, we want our roads to be supple, not brittle. When your skin is weathered and dry you use lotion to rejuvenate it. This is precisely how pavement preservation works. A fog seal is one of the first treatments. This is basically the introduction of a petroleum-based product back into the road, which helps the road become supple again. This helps prevent cracking and potholes.

For the first approximately ten years of a new pavement’s life. All is good. From years 10 to 17, we may fog seal the road a couple times before this treatment becomes ineffective. After that, we begin to use a slurry seal. This is also an oil-based product with sand that provides a more durable surface, which helps lengthen the lifespan of our roads. Keep in mind, the cost increases for each advanced level of preservation.

After about 25 years of use, these seal treatments become inadequate and the pavement begin to crack. Then we’ll implement more aggressive treatments such as crack and chip seal resurfacing.

Crack sealing keeps moisture out of the base materials underneath the asphalt. We perform crack sealing with our standard street operations. The crews will inject a polymer seal into the cracks. While we don’t often experience snow and extreme cold in Oro Valley, we see freezing temps every year. That’s why crack sealing is so important; it helps prevent potholes created by water freezing in the pavement. It also prevents water from undermining the pavement by saturating the soil below the road.
Chip sealing involves placing rubber-coated stones, approximately a quarter of an inch in size, along with an oil-based binder, over the recently crack-sealed road. This technique provides a new surface without removing any of the existing pavement.

The final and most aggressive preservation technique is milling and resurfacing. This takes place about 27 years into the pavement’s life and it entails scraping off the top layer of the street and installing new asphalt. This is the last measure used before a street is completely replaced with new pavement, which typically happens around the 30-year mark for a section of pavement.

An important thing to note about our Pavement Preservation Program is that we focus on our best roads first. This may seem counter-intuitive, but it leads to a higher return on investment as pavement preservation yields better results on roads that are in good condition than it does on roads in a lesser condition. Eventually, it doesn’t make fiscal sense to apply these treatments to older roads and, when the time comes, we schedule them for reconstruction.

La Cholla Boulevard is a good example. The road was deteriorating, but we had Regional Transit Authority funding to fix it because it’s a regional connection through Oro Valley. Tangerine Drive was the same way, with regional funding to rebuild it. Now Tangerine is fantastic and La Cholla will soon be as well. And once the La Cholla project is complete, our roads in good condition.

And that means pavement preservation will be even more important. We have limited money, and as we transition from an expanding community with new roads, to a community with a network of good roads that need to be maintained, that will change our approach to pavement preservation and require more resources. We refuse to take our eye off the ball and we will continue to maintain Oro Valley’s pavement and keep our roads in good condition. We have learned from other communities that if roads are neglected, the cost to restore them escalates to a point where it is impossible to recover.

So be sure to take care of your skin this summer. We’ll be doing the same thing for our roads. And as you drive through Oro Valley, please slow down and give the crews, both contractors and Town staff, working on the road some space. They’re working hard to provide quality roads for all of us.

For up-to-date information on our roadway projects, like the La Cholla Boulevard widening project, visit www.orovalleyaz.gov and subscribe to our email list on the homepage.

By Paul Keesler, P.E., Director, Public Works/Town Engineer - Explorer Newspaper, 3/20/19

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