(1) In addition to the levy authorized by Section 27-39-303, the board of supervisors may annually impose a countywide ad valorem tax levy or levies for the maintenance and/or construction of roads and bridges.

(2) For each fiscal year, the aggregate receipts from taxes levied for the maintenance and/or construction of roads and bridges pursuant to this section shall not exceed the aggregate receipts from this source during any one (1) of the immediately preceding three (3) fiscal years, as determined by the board of supervisors, plus an increase not to exceed ten percent (10%). The additional revenue from the ad valorem tax on any newly constructed properties or any existing properties added to the tax rolls or any properties previously exempt, which were not assessed in the next preceding year may be excluded from the ten percent (10%) increase limitation set forth herein.

(3) The ten percent (10%) increase limitation prescribed in this section may be increased an additional amount only as provided in subsection (4) of this section or when the county board of supervisors has determined the need for additional revenues and has held an election on the question of raising the limitation prescribed in this section. The limitation may be increased under this subsection only if the proposed increase is approved by a majority of those voting in an election held for such purpose. The resolution, notice and manner of holding the election shall be as prescribed by law for the holding of elections for the issuance of bonds by the county board of supervisors. Revenues collected for the fiscal year in excess of the ten percent (10%) increase limitation pursuant to an election shall be included in the tax base for the purpose of determining aggregate receipts for which the ten percent (10%) increase limitation applies for subsequent fiscal years.

(4) As an alternative to the procedure provided in subsection (3) of this section, the ten percent (10%) increase limitation prescribed in this section may be increased by an additional amount without an election thereon if the aggregate receipts from the levy authorized in this section and from all other county levies to which Sections 27-39-320 and 27-39-321 apply do not exceed one hundred ten percent (110%) of the aggregate receipts from all such levies during any one (1) of the immediately preceding three (3) fiscal years, as determined by the board of supervisors.

(5) Except as otherwise provided for excess revenues generated pursuant to an election under subsection (3) of this section and for excess revenues generated in accordance with subsection (4) of this section, if revenues collected as the result of the taxes levied for the fiscal year pursuant to this section exceed the increase limitation, then it shall be the mandatory duty of the board of supervisors to deposit such excess receipts over and above the increase limitation into a special account and credit it to the county road and bridge fund. It will be the further duty of such board to hold said funds and invest the same as authorized by law. Such excess funds shall be calculated in the road and bridge budget for the succeeding fiscal year. Taxes imposed for the succeeding year shall be reduced by the amount of excess funds available. Under no circumstances shall such excess funds be expended during the fiscal year in which such excess funds are collected.

(6) In any county where there is located a nuclear generating power plant on which a tax is assessed under Section 27-35-309(3), the term “the aggregate receipts from taxes” as used in this section shall be the portion of the “base revenue” as defined in Section 27-39-320 which is used for the maintenance and/or construction of roads and bridges.

(7) If a shortfall occurs in revenues from sources other than ad valorem taxes and oil and gas severance taxes budgeted for the county road and bridge fund during the 1987 fiscal year, then the county may levy a special ad valorem tax for the 1988 fiscal year in an amount the avails of which shall not exceed such shortfall; provided, however, that the aggregate receipts from all ad valorem levies for the maintenance and/or construction of roads and bridges for the 1988 fiscal year shall not exceed the aggregate receipts from this source for the immediately preceding fiscal year plus an increase not to exceed twenty percent (20%).

(8) If a shortfall occurs in revenues from oil and gas severance taxes budgeted for the county road and bridge fund during the 1987 fiscal year, then the county may levy a special ad valorem tax for the 1988 fiscal year in an amount the avails of which shall not exceed such shortfall. The avails of such special ad valorem tax shall not be included within the ten percent (10%) increase limitation. The ad valorem taxes levied to offset the shortfall shall be deemed to be ad valorem tax receipts produced in the 1988 fiscal year for the purpose of determining the limitation on receipts for the succeeding fiscal years.