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Traditional asphalt mixture design practices recognize the need for laboratory parameters, which relate to field performance throughout the life of the pavement. However, many design methodologies consider volumetric proportions and strength characteristics of the mixtures, which may not provide adequate insight into mixture performance. Laboratory testing that can ascertain an asphalt mixture's capability to resist common distresses is needed to complement current design methodologies. Distresses commonly associated with flexible pavement failure are fatigue cracking and permanent deformation (rutting). The Louisiana Department of Transportation and Development proposed specification modifications for 2013 to address the need for balanced mixtures (i.e., mechanistic laboratory evaluation to complement volumetric criteria). This paper presents Louisiana's experience with specification modifications to develop a balanced mixture as evaluated through the use of the Hamburg loaded wheel tester (HLWT) and semicircular bend (SCB) tests. Laboratory performance of 11 mixtures produced with the 2013 proposed specification modifications was compared with that of 40 mixtures produced under the 2006 specifications. Laboratory tests included HLWT and SCB to evaluate rutting and intermediate temperature cracking, respectively. The research showed that specification modifications did not adversely affect rutting or fatigue cracking resistance of the mixtures.

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Vehicle emission is a major source of air pollution in Dhaka. Old fleet, lack of maintenance, improper traffic and parking management, overloading, fuel adulteration etc. are responsible for high emissions from the vehicle sector. In this study, vehicle emissions have been measured on-road in Dhaka using an Automotive Gas Analyzer and Smoke Opacity Meter to determine the existing vehicle emission scenario in the city. Concentrations of carbon monoxide (CO) and hydrocarbons (HC) in the emissions from CNG/gasoline vehicles, and opacity of the emissions from diesel vehicles were measured. The results were compared with the corresponding national limit values. It was found that all types of CNG vehicles performed very well with more than 80% satisfying the corresponding limit values. Private cars ranked at the top in performance among the CNG/gasoline vehicles. Diesel vehicles were found as the worst polluters in the vehicle sector; emissions from about 75% of the diesel vehicles had opacity more than 65 HSU, the national limit value for emissions from diesel vehicles. Motor cycles were also highly polluting; 60% of the motor cycles emitted CO and HC concentrations higher than the respective national emission limit values.