System 4

Drawing of a typical System 4 application (Cold mill + ARAM + ARHM or conventional asphalt concrete)

An ARAM System 4 application is a System 3 application without a leveling course. This composite layering system is designed for arterial streets and highways, but can be used when the street conditions are not as bad as what is required for a System 3 application.

System 4 composite layering systems are also viable alternatives to reconstruction. By eliminating the leveling course (and, in some cases, the full width cold mill), there is a significant cost savings. In 2012, Caltrans utilized a System 4 application on Interstate 5 outside the City of Valencia applying hundreds of thousands of square yards. This is an excellent testament to the system's high performance and demonstrates how to maximize taxpayer dollars.

This system usually starts with a full width cold mill, but a header cut is sometimes all that is required. ARAM is then applied directly to the existing surface, followed by 1.2 to 2 inches of Asphalt-Rubber Hot Mix (ARHM) or conventional hot mix asphalt.

To find out more information about ARAM, call the WPMA at (213) 683-1300 or e-mail

1. Before an ARAM System 4 application

2. Full width cold mill

3. Applied ARAM (after sweeping)

4. Depth for overlay

5. ARHM or conventional hot mix asphalt overlay

6. Finished System 4

P.O. Box 227206
Los Angeles, CA 90022
(213) 683-1300

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