AFFORDABLE

USING CONCRETE TEXTURE AT THE TIME OF CONSTRUCTION IS FIVE TIMES MORE COST EFFECTIVE THAN INSTALLING AN ASPHALT RUBBER OVERLAY.

Asphalt rubber costs $3.9 BILLION dollars more than diamond grinding!!! 

 

Did we get your attention? Read on to learn more.

Why were Arizona's urban freeways constructed out of concrete pavement? In 1920, Maricopa County created the largest concrete pavement construction program of any county in the U.S. By the time the highway system was first constructed, the Valley already had long-term experience with both asphalt and concrete roadways and that is why concrete was chosen.

History validated this decision. The first section of concrete pavement placed in 1961 is still there 60 years later. It has incurred more than ten times the traffic it was designed for and is just over half as thick as the modern freeways constructed today.

 

When the freeway system was covered with asphalt rubber, there was no economic analysis conducted to determine the true long-term cost of ownership of an asphalt rubber overlay strategy. The decision was based on noise alone, and there was no consideration as to ultimate cost over time, property damage to vehicles from fly rocks raveling from the asphalt rubber, damage to existing concrete from the asphalt rubber removal process, or the roughness created by the raveled joints every 15 feet.

A recent ADOT study indicated that over a 30-year period, asphalt rubber costs $3.9 BILLION dollars more than diamond grinding to maintain the highway system. 

Arizona ranks number one in the U.S. for windshield damage claims. As asphalt rubber ages, the rocks it’s made from ravel off the road, producing a potential 33 BILLION fly rocks to damage windshields and auto paint. The resulting property damage (especially to windshields) increases insurance costs in Arizona, affecting everyone.

At the time of construction, the cost of one inch of asphalt rubber is more than the cost of adding an additional two inches of increased thickness of concrete, which would significantly increase the concrete service life.

Cars driving on a freeway that is half diamond ground concrete and half asphalt

DIAMOND GRINDING PILOT PROJECTS SHOW PROMISE AS COST-EFFECTIVE FIX FOR PHOENIX HIGHWAYS

By Randy Everett - Senior Division Administrator, Arizona DOT, Central District

Returning Arizona highways to Portland Cement Concrete might just prove beneficial using diamond grinding as an alternative to the standard mill and fill. The outlook suggests a $3.9 billion reduction in maintenance costs over a 30-year period.

WHAT HAPPENS WITH INADEQUATE INVESTMENTS?

 

The Arizona and federal gas taxes were last increased in 1991 and 1993, respectively. As a result, the buying power of money (funding) has decreased 30% to 40%, the wear-out rate on Arizona roads (traffic) has increased 30%–50%, and the federal auto fuel efficiency requirements have increased 40%. The outcome is agencies are woefully underfunded to maintain the state’s infrastructure. Unnecessary expenditures in the Valley, such as for asphalt rubber, are not only bad for the Valley but for the entire state. 

“In 2018, 43% of Arizona’s major roads were in poor or mediocre condition. Driving on poorly maintained roads costs Arizona drivers $3 billion a year in extra vehicle repairs and operating costs. The cost per motorist has risen to $576, which is $258 higher than in 2015.” – ASCE Arizona 2020 Report Card

The National Highway System in Arizona is declining due to inadequate funding. 

WE NEED TO SPEND OUR MONEY WISELY AND WHERE IT IS BEST USED!

Diamond ground concrete surfaces need significantly less maintenance than asphalt rubber, which requires maintenance every few years. Perpetual maintenance involves additional costs (higher taxes) and increased traffic disruptions. Note the decline in pavement condition in Arizona since using asphalt rubber, as shown in the graphic below.

A chart depicting the decline in pavement condition in Arizona over the last ten years
COST OF ROAD OWNERSHIP BY PAVEMENT TYPE
A chart depicting the 30-year cost of ownership between asphalt rubber ($7.7 billion) and diamond ground concrete ($3.8 billion)

ADOT 30-year cost

A chart depicting the lifespan of one inch of asphalt rubber (10-15 years) to 2 inches of concrete pavement (50-60 years)

At the time of construction, one inch of asphalt rubber costs more than an additional two inches of concrete thickness.

Cars driving on an asphalt freeway with a note pointing to a raveled joint in the road; text reads "33.5 Billion Fly Rock to Damage Windshields and Auto Paint"

Asphalt rubber raveling causes property damage.

The cover of the Arizona Section of the American Society of Civil Engineers report card for Arizona roads in 2020, featuring an image of a desert highway at sunset
The Arizona Section of the American Society of Civil Engineers report card for Arizona indicates the roads earned a D+; featuring an image of a car driving through a desert in the daytime

Photo credit: ASCE Arizona Section

Photo credit: ASCE Arizona Section

WHAT DO WE WANT OUR FUTURE TO BE?