ASTM E1448/E1448M-09(2023)

4.1?Measures obtained by a response-type system depend primarily on the vehicle design and condition, the load, the measuring speed, and a host of environmental conditions. Even with control of all significant variables, the response of every vehicle is unique. Thus, raw measures from such a system are not reproducible with other systems.

4.2?The calibration described in this practice provides a method for converting the raw output of a particular response-type system to a reproducible standard roughness scale.

4.3?The estimate of the standard roughness index made by transforming an RTSN is subject to three types of error:

4.4?Periodic verification is essential to ensure that the calibration remains valid.

1.1?This practice describes equipment and procedures for the calibration of systems used for measuring vehicular response to pavement roughness. Such systems are referred to as response-type systems. (See Test Method E1082.)

1.2?The response-type system includes the driven vehicle, the driver and contents of the vehicle, the towed trailer (if one is used with the system), and a device called a road meter that measures the vehicle response to pavement roughness. The road meter may be mounted in an automobile, van, or in a towed trailer. Response-type (road meter) devices covered in this practice include: devices measuring the relative axle-body motion of a vehicle, devices measuring the vertical acceleration of the vehicle body, and devices measuring the vertical acceleration of the vehicle axle.

1.3?The calibration procedures described in this practice are limited to the use of the simulations described in Practice E1170.

1.4?This practice is not intended to apply to pavement roughness measuring equipment whose output is not influenced by the response of the host vehicle.

1.5?The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.6?This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7?This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.