Pavement quality testing instruments are devices that measure pavement evenness, flexibility, and asphalt compaction. They are commonly used by civil engineers and construction companies to analyze and determine pavement quality. High-low detectors measure planeness of pavement surfaces, such as highways, and require only one operator to detect, register, and dye mark fluctuations that need to be ground down or filled. Deflection devices, such as the Benkelman Beam, measure the deflection of flexible pavement under moving wheel loads to analyze pavement structure.