§201.16. Standard for locomotive load cell test stands. — Inbound Citations

(3) The data shall be analyzed to determine the levels exceeded 99%, 90%, and 10% of the time, i.e., L99, L90, and L10, respectively. The value of L90 is considered a valid measure of the A-weighted sound level for the standards in § 201.16 only if the difference between L10 and L99 has a value of 4 dB or less. If a measured value of L90 is not valid for this purpose, measurements may be taken over a longer period to attempt to improve the certainty of the measurement and to validate L90. If L90 is valid and is less than the level in applicable standards for these source types, the sources are in compliance. If the measured value of L90 is valid and exceeds the initial 65 dB requirement for any of the source types that appear to be affecting the noise environments, the evaluation according to the following paragraph (c) is required.