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This paper compares pavement texture measurements from a three-dimensional (3-D) line-laser scanner and from a two-dimensional (2-D) spot-laser circular track (CT) meter to determine whether correlations exist between their texture parameters. Measurements with the two devices were taken simultaneously on pavements at the Minnesota Department of Transportation MnROAD test facilities. The 3-D texture heights were decomposed by using a discrete wavelet transform to separate microtexture from macrotexture. Macrotexture parameters from the two devices were analyzed. A linear relationship, with an R2value of .94, was found between the 2-D mean profile depth and the 3-D digitally simulated mean texture depth. Similarly, the R2value was .98 between the 2-D root mean square roughness and the 3-D root mean square deviation. These correlations are essential and can be used by road agencies to predict texture indexes between 2-D and 3-D measurements for data comparison or quality assurance when equipment is of different dimensions.

This paper compares pavement texture measurements from a three-dimensional (3-D) line-laser scanner and from a two-dimensional (2-D) spot-laser circular track (CT) meter to determine whether correlations exist between their texture parameters. Measurements with the two devices were taken simultaneously on pavements at the Minnesota Department of Transportation MnROAD test facilities. The 3-D texture heights were decomposed by using a discrete wavelet transform to separate microtexture from macrotexture. Macrotexture parameters from the two devices were analyzed. A linear relationship, with an R2value of .94, was found between the 2-D mean profile depth and the 3-D digitally simulated mean texture depth. Similarly, the R2value was .98 between the 2-D root mean square roughness and the 3-D root mean square deviation. These correlations are essential and can be used by road agencies to predict texture indexes between 2-D and 3-D measurements for data comparison or quality assurance when equipment is of different dimensions.

The spring thaw period significantly reduces the bearing capacity of lowvolume asphalt roads. To compensate for the reduced bearing capacity, highway agencies apply spring load restrictions (SLR) to limit the damage caused by heavy loads during the period when the road is weakened by thaw. Although the imposition of SLR may reduce road damage, it has a major impact on truck productivity. An alternative to reducing truck loads during the spring is the reduction of truck tire pressure. The reduced tire pressure lowers the tire-pavement contact pressure and the associated damage during the spring period. In 2008, asphalt strain gauges were installed in a section of a low-volume haul road in Manitoba, Canada. Field testing was conducted in the spring and fall of 2009 with a double semitrailer or B-Train equipped with a semiautomated tire pressure control system. The tests were conducted at various loads and speeds and at normal and reduced tire pressures. The results of the field testing showed that when the tire pressure was reduced by 50%, the measured maximum tensile strain at the bottom of the asphalt layer decreased by an average of 15% to 20%. The effects of gauge orientation, truck speed, and tire offset from the strain gauge were analyzed and are presented.

The spring thaw period significantly reduces the bearing capacity of low-volume asphalt roads. To compensate for the reduced bearing capacity, highway agencies apply spring load restrictions (SLR) to limit the damage caused by heavy loads during the period when the road is weakened by thaw. Although the imposition of SLR may reduce road damage, it has a major impact on truck productivity. An alternative to reducing truck loads during the spring is the reduction of truck tire pressure. The reduced tire pressure lowers the tire–pavement contact pressure and the associated damage during the spring period. In 2008, asphalt strain gauges were installed in a section of a low-volume haul road in Manitoba, Canada. Field testing was conducted in the spring and fall of 2009 with a double semitrailer or B-Train equipped with a semiautomated tire pressure control system. The tests were conducted at various loads and speeds and at normal and reduced tire pressures. The results of the field testing showed that when the tire pressure was reduced by 50%, the measured maximum tensile strain at the bottom of the asphalt layer decreased by an average of 15% to 20%. The effects of gauge orientation, truck speed, and tire offset from the strain gauge were analyzed and are presented.

For low-voltage micro-grid systems with multiple micro-sources with different rated capacities, the performance of load power distribution in proportion to the capacity of micro-sources is very important to the stability and efficient operation of the system. The inverse droop control strategy has the problem of active power distribution error due to the unbalanced line impedance of micro-grid. The virtual impedance can suppress this error, but the traditional virtual impedance method will lead to large voltage sag. Therefore, a novel inverse droop control method with virtual impedance is proposed, which can realize the power distribution in proportion to capacity and ensure the stability of voltage and frequency. Finally, a low-voltage micro-grid system with six specific micro-sources is built on the PSCAD / EMTDC platform to simulate the multi-mode operation under Island / grid-connected mode, and the effectiveness of the control strategy is verified comprehensively.