(a) The District Commander may modify the requirements for the display of lights and other signals on any bridge when a change in local conditions warrants the modification.

(b) The District Commander may exempt bridges over waterways with no significant nighttime navigation from the lighting or other signal requirements in this part.

(c) The District Commander may prescribe special lighting or other signals in specific cases when the lighting or other signals in this part may not provide adequately for the safe passage of vessels.

(d) While a bridge is under construction, the District Commander prescribes the temporary lights and other signals to be displayed for the protection of navigation.