49 CFR §670.11

1. (a)The Administrator may conduct investigations, inspections, audits and examinations, and test the equipment, facilities, rolling stock and operations of a recipient's public transportation system.
2. (b)To the extent practicable, the Administrator will provide notice to a recipient prior to initiating any activities carried out under the authorities listed in paragraph (a) of this section.
3. (c)The Administrator will conduct activities carried out under this section at reasonable times and in a reasonable manner, as determined by the Administrator.
4. (d)In carrying out this section, the Administrator may require the production of relevant documents and records, take evidence, issue subpoenas and depositions, and prescribe recordkeeping and reporting requirements.