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The most common road surfaces today are Hot Mix Asphalt (HMA) pavement and Portland Cement Concrete (PCC) pavement. Both types of pavement can be modified to create quieter pavement surfaces.
Conventional Dense-Graded HMA is used on most of Washington State's highways. It has a tight surface with few air pockets, which minimizes the ability of water to enter its surface. As a result, dense-graded asphalt pavements have good durability and skid resistance, but also tend to be slightly noisier than Open Graded Friction Course (OGFC) pavement. Open Graded Friction Course (OGFC) asphalt pavement is quieter than dense-graded HMA because it has "negative texture" - air pockets in the pavement that capture road noise. The down side of OGFC's is that they have a much shorter pavement life than dense-graded asphalt pavements.
Transverse Tined Texture. A concrete pavement is used on heavily-traveled urban corridors because of its durability. Most concrete surfaces (like the own shown above) are "tined" to provide skid residence for drivers. Tining is created by dragging a mechanical rake across freshly laid concrete to create shallow channels. Transverse tined concrete is one of the most durable but also one of the noisiest pavement types with a typical range of 103 to 110 decibels. Carpet Drag Texture One of the alternative textures being evaluated for quieter concrete pavement is the carpet drag finish. It is created by dragging a piece of astro-turf carpet down the pavement in the direction of travel. It produces a very fine texture without the shallow channels of the transverse tining, and is thus quieter. Longitudinal Tined Texture is another finishing method that is quieter than transverse tining. It is produced by dragging a rake with metal tines along the length of the pavement to produce shallow channels in the direction of travel. Longitudinal Tined Texture looking down the lane. Typical noise level for longitudinal tined concrete ranges from 101 to 106 decibels. Next Generation Concrete Surface (NGCS) is a texture applied to existing roadway to reduce the tire/pavement noise from a concrete pavement. NGCS is characterized by flat higher land areas and deep grooves running in the longitudinal direction similar to longitudinal tining. The grooves provide a space to absorb some of the noise produced from tires similar to the tiny air holes in open graded friction course asphalt pavements. Typical sound intensity levels of the NGCS range from 99 to 101 decibels. Next Generation Concrete Surface (NGCS) close-up view showing the wide flat land areas and the deep grooves spaced 1/2 inch apart. Conventional Diamond Grinding (CDG) is, as the name implies, the standard method used to diamond grind concrete pavement. It produces a flat surface with fins of concrete that protrude from the pavement. This positive texture produces more noise than the negative texture of the grooves used for the NGCS. The typical range of sound intensity levels for CDG is 100 to 104 decibels.