33 CFR §117.39

1. (a)When there have been no requests for drawbridge openings for at least two years, a bridge owner may request in writing that the District Commander authorize the drawbridge to remain closed to navigation and to be untended.
2. (b)The District Commander may:
   1. (1)Authorize the closure of the drawbridge;
   2. (2)Set out any conditions in addition to the requirement in paragraph (d): and
   3. (3)Revoke an authorization and order the drawbridge returned to operation when necessary.
3. (c)All drawbridges authorized to remain closed to navigation, under this section, must be maintained in operable condition.
4. (d)Authorization under this section does not:
   1. (1)Authorize physical changes to the drawbridge structure, or
   2. (2)Authorize removal of the operating machinery.
5. (e)Drawbridges authorized under this section to remain closed to navigation and to be untended are identified in subpart B of this part.