ADOT Making Good Use of Asphalt-Rubber on
Major Design/Build Freeway Projects in Phoenix Area
Drivers, nearby residents noticing difference on stretch of US 60.

 The Arizona Department of Transportation, which started using open graded friction courses in the 1970s, has turned to using an Asphalt-Rubber, high binder, open graded mix on some major freeway improvement projects in the greater Phoenix area. Most recently, an approximately 3 / 4 " layer of Asphalt-Rubber was applied to the Superstition Freeway (US 60) between I-10 and the Loop 101 freeway in Tempe, as part of an ongoing design-build project to renovate the freeway. Reaction from drivers and nearby residents has been very positive, wit many saying they've noticed the smoother ride and a reduction in noise following the application of Asphalt-Rubber. In fact, letters to the editors of local newspapers praising the use of the material are common.

Asphalt-Rubber was previously used on an I-17 improvement project between Thomas Road and Peoria Avenue, which wrapped up in fall 2000. ADOT also plans to use rubberized pavement on an upcoming project to add carpool lanes to State Route 51 between I-10 and Shea Boulevard in Phoenix. The work is scheduled to start by spring 2003.

In May, 2001 ADOT awarded a $184.2 million contract to RPA member Granite Construction and their contract partner, Sundt Construction, for a major design/build freeway improvement project on 13 miles of the US 60 in the Phoenix/Tempe/Mesa areas of Maricopa County. The project includes adding HOV lanes, a freeflow ramp connecting the HOV lanes between the I-10 and the US 60, additional traffic lanes on certain sections, huge earthern berms, new soundwalls and other major improvements. The 36 month con-tract is currently ahead of schedule and the contractors estimate it will be completed in 26 months. The US 60, built in the 70s, is concrete pavement and has grown noisier with increased traffic over the years. While motorists and residents reacted predictably to the construction inconveniences, one aspect of the project was accepted enthusiastically. That was the ADOT decision to resurface the freeway with Asphalt-Rubber open graded surface course.

Because few similar freeway resurfacing projects have been documented for noise reduction, RPA is partnering with Arizona State University (ASU), Department of Civil and Environmental Engineering, to measure the freeway noise prior to and after the resurfacing with the Asphalt-Rubber. The results bear out what the Arizona public has known all along without benefit of sophisticated equipment, Asphalt-Rubber makes a significant reduction in noise. The measurements below were taken by Dr. Han Zhu, ASU and Douglas Carlson, RPA Deputy Director between 11:00 am and 1:00 pm on a weekday at three locations near the Kyrene Overpass of the US 60.

Photo courtesy of Arizona DOT