"Provided that no local tax rate or mill levy shall be increased without further voter approval and for the purpose of providing additional funding and for street and road improvements, shall the City of Montrose be authorized to collect, retain and expend solely on street and road improvements all excess revenues and other funds received in the 2005 calendar year and in each subsequent calendar year thereafter without further voter approval, notwithstanding the limitations of Article X, Section 20 of the Colorado Constitution."