33 CFR 116.20: Detailed investigation.

(a) When the Chief, Office of Bridge Programs determines that a Detailed Investigation should be conducted, the District Commander will initiate an investigation that addresses all of the pertinent data regarding the bridge, including information obtained at a public meeting held under § 116.25. As part of the investigation, the District Commander will develop a comprehensive report, termed the “Detailed Investigation Report”, which will discuss: the obstructive character of the bridge in question; the impact of that bridge upon navigation; navigational benefits derived; whether an alteration is needed to meet the needs of navigation; and, if alteration is recommended, what type.

(b) The District Commander will forward the completed Detailed Investigation Report to the Chief, Office of Bridge Programs for review together with a recommendation of whether the bridge should be declared an unreasonable obstruction to navigation and, if so, whether an Order to Alter should be issued.