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INTRODUCTION
Pavement surface texture plays important roles in roadway safety and noise
issues. More than 32,000 deaths and 2.3 million injuries occurred in more than 6
million vehicle crashes in the U.S. in 2014 (NHTSA 2016) and about 16 percent of
those crashes took place on wet pavement (FHWA 2016). The two main causes
of wet weather crashes are: 1) hydroplaning (loss of contact between tires and the
pavement surface due to a film of water) and 2) poor visibility due to splash and
spray. Inadequate friction also contributes to many dry-weather accidents,
particularly in work zone and intersections where braking and unusual vehicle
movements are common.
There are many sources of sound in the highway environment, including vehicle
sounds (e.g., engine and exhaust noise, etc.), sound due to the passage of air
around the and through the vehicle, and the interaction of vehicle tires and the
pavement surface. Tire-pavement interaction is generally the predominant source
of sound for cars and trucks at vehicle speeds greater than 20 mi/h (32 km/h) and
30 mi/h (48 km/h), respectively. When other factors are held constant, traffic noise
levels vary mainly with the characteristics of the pavement surface, e.g., the
porosity and texture (ACPA 2006).
The selection, design and construction of concrete pavement surface texture
requires the consideration of both noise and safety concerns, as well as durability
and cost - often competing factors! This Tech Brief complements FHWA
Technical Advisory T 5040.36 (FHWA 2005) by: 1) providing additional details
concerning how pavement texture affects roadway noise and safety; 2) describing
current concrete pavement surface texturing methods and their impacts on
roadway noise and safety; and 3) providing guidance concerning best practices
for concrete pavement texture selection, specification and construction.
CHARACTERIZING SURFACE TEXTURE
Surface Texture Definitions and Their Impacts on Noise and Safety
Overall pavement surface texture is comprised of the contributions of aggregate
texture and gradation, pavement finishing techniques, pavement wear, and more.
The resulting surface texture can be characterized in terms of texture depth and
feature length or wavelength. Different combinations of texture depth and
wavelength have different effects on tire-pavement interactions, such as noise and
friction.
The Permanent International Association of Road Congresses (PIARC) has
proposed the following four categories of pavement surface characteristics based
on measurements of depth (or amplitude) and wavelength: micro texture,
macro texture, mega texture and unevenness (roughness) (PIARC 1987). These
four categories and their impacts on tire-pavement interaction are presented
graphically in figure 1 (after Rasmussen et al. 2004) and are described below.
Micro texture
Micro texture is defined as having wavelengths of 0.0004 to 0.02 inches (1μm to
0.5 mm) and depth of less than 0.008 inches (0.2 mm) (PIARC 1987). In concrete
pavements, micro texture is typically provided by the fine aggregate (sand) in the
The images above are Applied Pavement Technology originals concrete mixture.
Негізгі бет PQC (Pavement Quality Concrete) ROAD ME TEXTURING कैसे करते है?
Пікірлер: 24