(a) The department of transportation is empowered to lower the speed limits prescribed in § 55-8-152 in business, urban or residential districts, or at any congested area, dangerous intersection or whenever and wherever the department shall determine, upon the basis of an engineering and traffic investigation, that the public safety requires a lower speed limit.

(b) Appropriate signs giving notice of the lower speed limit shall be erected by the department at such places or put on the highway where the prescribed speed limits are effective.

(c)

(1)

(A) The legislative authorities of municipalities shall possess the power to prescribe lower speed limits on highways designated as state highways in their respective jurisdictions when, on the basis of an engineering and traffic investigation, it is shown that the public safety requires a lower speed limit.

(B) Engineering and traffic investigations used to establish special speed zone locations and speed limits by municipalities on state highways shall be made in accordance with established traffic engineering practices and in a manner that conforms to the Tennessee manual on uniform traffic control devices (MUTCD). The investigations shall be documented and documentation shall be maintained by the jurisdiction performing or sponsoring the investigation.

(C) All signs, signals and other forms of public notification of the speed limits, road hazards and other traffic conditions shall comply with the MUTCD.

(2) The legislative bodies of municipalities shall also possess the power to prescribe lower speed limits within certain areas or zones, or on designated highways, avenues or streets that are not designated as state highways in their respective jurisdictions, and to erect appropriate signs and traffic signals.

(d) The legislative body of any county, except the legislative bodies of any counties having a commission form of government, has the power to prescribe such lower speed limits as it may deem appropriate on any road being maintained by the county and shall erect appropriate signs and traffic signals. In those counties having a commission form of government, the board of commissioners has the power prescribed in this section.

(e) A violation of the speed limits established by the department pursuant to subsection (a) is a Class B misdemeanor, punishable by fine only, when employees of the department or construction workers are present. The department, or its agents, are directed to indicate the presence of workers or department employees with signs with flashing amber lights; provided, that this penalty is applicable in highway construction zones only to those speeding violations that have been detected by radar, infrared or similar detection devices. The amount of the fine imposed pursuant to subsection (a) for violations that occur in work zones where the speed limits have been reduced by the department and when employees of the department or construction workers are present shall be not less than two hundred fifty dollars ($250).