A judge gave the city of Russellville approval to go ahead with an election today on a property-tax increase. The increase was previously approved by the City Council. Opponents of the increase sought the election after the tax hike was approved in September. They gathered signatures on petitions seeking a vote on the measure. The special election was challenged in court by a group of firefighters who claimed some signatures had been forged on the petitions, and that the wording of the ballot measure is unclear. Special Judge John S. Patterson of Clarksville ruled from the bench Monday that the vote could go forward.