49 CFR § 1.22 - Deputy Secretary.

Along with the Secretary, the Deputy Secretary exercises oversight of all of the OST components, as well as each of the Operating Administrations, and overall planning, direction, and control of the Department's agenda. The Deputy Secretary:

(a) May exercise the authority of the Secretary, except where specifically limited by law, order, regulation, or instructions of the Secretary;

(b) Serves as the Chief Operating Officer; and

(c) Serves as the Chief Acquisition Officer.