PHOENIX (3TV/CBS 5) - The rubberized asphalt surfaces put down on Valley freeways in the past 10 to 15 years are now reaching the end of their life span, according to officials from the Arizona Department of Transportation. That has resulted in a growing number of potholes, cracks and deep gouges along Valley freeways.

[Check your area: Potholes, cracks on Phoenix area freeways]

"We designed it to last 10 years and most of them (the surfaces) have been down for more than 10 years, so what we’re starting to see is (sic) signs of age," said Julie Kliewer, who is the state construction and materials engineer.

ADOT began widespread use of rubberized asphalt on Valley freeway surfaces around 2005. Crews laid a 1-inch-thick layer of the asphalt on top of the gray Portland cement that had been the surface of metropolitan freeways for years, because of its durability. Portland cement has a life span of 40 years or more.

[WATCH: Pothole problems in Phoenix area due to shortened road lifespan]

The rubberized asphalt is considered quieter, provides a smoother ride and reduced "splash" during rainstorms. But as it ages, those beneficial qualities decrease, according to studies reviewed by CBS 5 Investigates.

"All in all, they have performed better than expected. It’s just we’ve hit, we’re starting to hit end of life," said Kliewer.

Age, along with the wet winter, has translated into the rougher ride some Valley motorists are experiencing today.

"You hit a pothole and it breaks that rubber mount in the top of the strut," said Mike Stanley, as he pointed to the front end of a minivan on a lift.

Stanley owns Stanley's Service Center, and he says he's seen an increase in the number of customers with damaged front suspensions.

"Well, me being in the automotive business, I see dollar figures," said Stanley after we asked him what goes through his mind when he makes his commute on Valley freeways.

CBS 5 Investigates traveled every major Valley freeway over a week's time, and counted potholes, cracks and gouges in the rubberized asphalt surface. We then plotted the data on a map, to locate where the worst sections of freeways are found.

We did not count the normal cross-freeway cracking that occurs as a result of the sections of concrete beneath the surface. We were looking for signs of wear and tear.

The worst sections include Interstate 17 from Dunlap north to the Loop 101, as well as Interstate 10 west of the Deck Park Tunnel, up to and past the construction near the new Loop 202 interchange.

Other sections that have large numbers of potholes, cracks and gouges include the U.S. 60 through Mesa and Interstate 10 north of Ahwatukee.

ADOT officials say they are working on plans to address the problem, but as of Sunday, there is no funding source to redo the freeway surfaces.

"That’s a challenge the pavement engineers deal with all the time because pavements wear out," said Kliewer.

ADOT has begun to apply a coating that could extend the life of the asphalt, but officials admit that it is just a temporary fix.

They still believe it was a smart decision to cover the Portland cement surface with the rubberized asphalt because of the benefits it gave during its life span.

Morgan Loew's hard-hitting investigations can be seen weekdays on CBS 5 News at 6:30 p.m. and 10 p.m.

Copyright 2019 KPHO/KTVK (KPHO Broadcasting Corporation). All rights reserved.

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