The 2018 London municipal election will be conducted using the ranked ballot voting system, council decided Monday night.

At a special meeting of city council, a by-law was enacted to use the ranked ballot method of voting instead of the traditional first past the post method for Municipal Council.

London could become the first Canadian municipality where voters use this system to elect their municipal council.

Using the ranked ballot voting system, voters rank the candidates in order of preference on the ballot: first, second, third.

All votes are counted, and if one candidate does not have at least 50 per cent plus 1 of the votes, the candidate with the fewest number of votes is eliminated and the ballots are counted again, this time using the next candidate choice from ballots where the first choice candidate was eliminated.

The process is repeated until a winning candidate is determined.

Under the traditional first past the post system, voters in London selected just one candidate for councillor and one for mayor, and the candidate with the highest number of votes won.

Council needed to approve the ranked ballot voting by-law by May 1, according to the Municipal Elections Act, 1996, for it to apply to the 2018 municipal election.

All members of council, the mayor and city councillors, must be selected using this method. School board trustees will continue to be voted for using the first past the post system.

Moving to a ranked ballot voting system will increase the cost of administering the election by an estimated $322,500.

The next municipal election will be held on Oct. 22, 2018.