Sec. 155.6. Emergency or unusual conditions

The Commissioner of Transportation may, by the erection of signs, signals or other traffic control devices, alter or modify the provisions of this Part to adequately protect the public at locations where emergency or unusual conditions occur or exist as a result of the construction or reconstruction on a restricted highway. These alterations or modifications shall have the same force and effect as though they were specifically set forth in this Part and shall remain in force until the condition is considered by the commissioner to be safe and the erected signs, signals or other traffic control devices have been officially removed.