High-speed texture measurement of pavements.
This study was conducted to validate high-speed texture measuring equipment for use in highway applications. The evaluation included two high-speed systems and a new static referencing device. Tests were conducted on 22 runway and taxiway test sections from the National Aeronautics and Space Administration's Wallops Flight Facility and 7 surfaces from Virginia's Smart Road. Texture estimates recorded with the high-speed (dynamic) equipment correlated extremely well with estimates made with static referencing methods. The system developed by International Cybernetics Corporation was very functional for most conventional highway surfaces. However, a better correlation may be achieved with the referencing methods by using a system (such as the MGPS surface system developed by the Federal Highway Administration) that produces the American Society for Testing and Materials' standard mean profile depth. Finally, an analysis conducted using the CTMeter (circular track meter, a laser-based but static system) demonstrated an important advantage of combining indices produced from high-definition surface profiles. By comparing the mean profile depth with the root mean square data for a particular surface, it is possible to characterize more fully the shapes that contribute to a pavement's macrotexture.
Characterizing the Macrotexture of Asphalt Pavement Designs in Connecticut
In response to a Federal Highway Administration Technical Advisory entitled Surface Texture for Asphalt and Concrete Pavements, the Connecticut Department of Transportation (ConnDOT) has begun to establish targets for pavement texture depth on high-speed facilities by characterizing the macrotexture of different ConnDOT hot mix asphalt (HMA) pavement mixes. The results of this effort are presented in this paper. Pavements evaluated include SuperPave mixes with nominal maximum aggregate sizes of 0.187-in., ¼-in., 3/8-in. and ½-in. The mean profile depth (MPD) and estimated texture depth of each were measured with a high-speed laser sensor (laser profiler) mounted to ConnDOT’s Dynatest 1295 Pavement Friction Tester. Laser profiler and Circular Track Meter (CTMeter) texture measurements were taken and compared at the Virginia Smart Road facility in Blacksburg, Virginia, in order to validate previously taken laser profiler measurements in Connecticut. Validation of the laser profiler measurements was necessary because laser profilers have not been used extensively in practice. The linear association comparing measurements taken with these two devices was relatively strong (R²=0.80) The laser profiler appears to provide a viable macrotexture measurement. MPD was the measure used to characterize the macrotexture of the above ConnDOT HMA mixes. The characterizing MPDs measured for the ConnDOT mixes ranged between 21 to 22-mils for the ½-in. mix, 15-mils for 3/8-in. mix, 12 to 15-mils for the ¼-in. mix, and -1 to 4 mils for the 0.187-in. mix.
Energy
Energy is often defined as the ability to do work. There are many forms of energy. A few examples include; Gravitational energy, Kinetic energy (energy of motion), Thermal energy (heat energy), Potential energy. Potential energy is the energy something has based on its position in the universe. A stretched elastic band has potential energy. A rock held up in the air has potential energy based on its position.