Developing a Hong Kong based speed correction factor by CPX method

A systematic procedure for developing speed correction factor to adjust measured tyre/road noise is proposed in this paper. The draft ISO/CD 11819-2 on the Close-Proximity method to measure tyre/road noise stipulates that speed correction is needed to convert the tyre/road noise level at the sampling speeds to that at the reference speeds. However, the ISO standard does not mention the exact methodology for developing the speed correction factor development, although it recommends local authorities to develop their own. In this study, the tyre/road noise and speed data over 59 runs on a high speed porous asphalt surface is recorded by our CPX trailer in Hong Kong. The instantaneous noise and speed data are then analysed using this proposed procedure and the set of speed correction factor developed is found to be more stable and repeatable.