Any election which was held prior to the effective date of this act for the approval of a tax to be levied by Rossville township, in Shawnee county, to raise funds for township road improvements in accordance with Kan. Stat. Ann. §§ 80-1413 and which had notice thereof first published 17 days prior to the election instead of 21 days prior to the election is hereby validated. The Rossville township board may levy the tax in the amount and for the purpose approved by the voters at the election.