ASTM E1448/E1448M-09 (R2015) PDF Download

The ASTM E1448/E1448M-09 (R2015) standard provides a method for calibrating response-type systems that measure the vehicular response to pavement roughness. These systems include the vehicle, driver, towed trailer (if applicable), and a device called a road meter. The road meter measures the vehicle's response to pavement roughness, such as relative axle-body motion or vertical acceleration.

The calibration process involves converting the raw output of a response-type system to a reproducible standard roughness scale. This calibration is achieved by correlating the system's measurements with standard roughness index values obtained from calibration sites located on representative roads. An equation is then derived to estimate the standard roughness index from the response-type system's measurements.

The calibration process takes into account three types of error. First, there is random error (repeatability) inherent in the response-type system, which can be reduced by performing repeated measurements and averaging the results. Second, there may be bias error in the calibration equation, which should be minimized through proper calibration practices. Finally, there is a standard error of the estimate, which is constant for a specific combination of the response-type system and site but varies with site selection. This error limits the accuracy of the standard roughness estimate and can be estimated from data collected during the calibration.

Periodic verification is necessary to ensure the ongoing validity of the calibration. This standard practice applies to response-type systems that are influenced by the vehicle's response to pavement roughness and uses simulations described in Practice E1170. It is not intended for use with pavement roughness measuring equipment that is not affected by the vehicle's response.