Mitigating transportation noise is a major concern for Departments of Transportation (DOT) nationwide. From a responsibility standpoint, once a noise source leaves the boundary of the property, the noise control falls under the jurisdiction of the DOT. In the past, mitigation by the DOT was typically accomplished by erecting a sound barrier. If there was more noise or louder noise, a larger wall was used. As construction of these walls is prohibitively expensive, DOTs are increasingly interested in mitigating noise from the source. In order to investigate noise being produced at the source, the on-board sound intensity method was utilized to investigate quiet pavements. The method revealed the acoustical properties of both conventional pavements and quiet pavements. This research also led to the investigation of the effects of vehicle speed, effects of temperature and effects of different consumer tires and the role each plays in the generation of noise at the tire pavement interface.