Historical textIn force on Oct. 1, 2003Source: annual CFR editions 1996–2008

§ 325.75 Ground surface correction factors. 1

Wording first on file in the 1996 annual edition, superseded by the 2009 annual edition.

govinfo, 2003 edition ↗

Compare with

Before Jan. 1, 2017 the record is one snapshot per annual CFR edition, revised as of October 1. This is the 2003 edition's wording. An amendment that took effect between Oct. 1, 2003 and Oct. 1, 2003 would not appear until the next edition, so check the citations below and the Federal Register for exact effective dates.

49 CFR § 325.75 — Ground surface correction factors. 1. Text in force on October 1, 2003. This wording effective October 1, 1996 to October 1, 2009. Source: govinfo, 2003 edition, https://www.govinfo.gov/app/details/CFR-2003-title49-vol4/CFR-2003-title49-vol4-sec325-75. Retrieved from FMCSR.com, https://fmcsr.com/reg/325.75?asof=2003-10-01, on October 26, 2026. Unofficial compilation; verify against the official source.

¹ Table 1, in § 325.7 is a tabulation of the maximum allowable sound level readings taking into account both the distance correction factors contained in § 325.73 and the ground surface correction factors contained in § 325.75.

(a) Highway operations. When measurements are made in accordance with the rules in subpart D of this part upon a test site which is “hard,” a correction factor of 2 dB(A) shall be subtracted from the maximum observed sound level reading generated by the motor vehicle to determine whether the motor vehicle conforms to the Standards for Highway Operations, 40 CFR 202.20.

(b) Stationary Test. When measurements are made in accordance with the rules in subpart E of this part upon a test site which is “soft,” a correction factor of 2 dB(A) shall be added to the numerical average of the recorded maximum observed sound level readings generated by the motor vehicle to determine whether the motor vehicle conforms to the Standard for Operation Under Stationary Test, 40 CFR 202.21.

Amendment history

2 distinct wordings on file since Oct. 1, 1996

Oct. 1, 2009 → presentannual editions 2009–2016diff vs. previous
Oct. 1, 1996 → Oct. 1, 2009annual editions 1996–2008viewing

A new entry appears whenever the regulatory words change between government snapshots. Day-precise from the eCFR (2017 onward); before that, one snapshot per annual CFR edition (revised as of October 1). Bracketed citations are the Federal Register history printed with the section.