11.1.5 COMPLIANCE
(a) When tested in an anechoic chamber meeting the requirements of ISO
3745 (18-22 deg C, 45%-65% rel. hum., 990-1025 millibars), the horn
shall produce a minimum sound pressure level of 143 dB(A) at one meter
from the front of the horn. The railway shall retain the horn manufacturers
Certificate of Compliance and test records for not less than 10 years.