Where the Board of Aldermen determines that improvements, such as the construction of streets, the widening of streets, automatic traffic signals, the dedication of land for street construction or widening, culverts or bridges, are required by reason of the anticipated increase in traffic incidental to the proposed use and development of property zoned or rezoned in the "E" Planned Shopping Center District, such construction or satisfactory security for such construction shall be required in advance of the owner or developer of such property, unless such construction shall be available through agencies of the Federal Government, the State of Missouri or the County of St. Louis before the issuance of a building permit. In cases where the proposed amendment of this Article by reclassification of property into the "E" Planned Shopping Center District is being considered, the Board of Aldermen may require such assurances or guarantees, in whatever form it deems necessary or advisable, to be given the City by the proposed developer of the property as will satisfy the Board insofar as reasonable under the circumstances.