Open Graded Asphalt is used in Australia and overseas as a wearing course to provide increased safety in wet weather (through reduced surface water and spray during rain) and reduced noise levels. Open Graded Asphalt is a porous asphalt mix formulated to provide large voids (in excess of 20%) to allow surface water to drain away and hence increase safety for the motorist.

The demand for low traffic noise surfacing has greatly increased in the last few years, especially in urban areas. As an indication, current Australian Open Graded Asphalt mix designs are reported to reduce average noise levels by up to 3dB(A) compared to Dense Graded Asphalt and up to 5dB(A) compared with Spray Seals.