In an effort to avoid multiple, costly runoff elections, Los Angeles County supervisors unanimously voted today to investigate whether the county can save money and boost turnout through instant runoffs.

Instant runoffs prevent repeated special primary elections by allowing voters to rank candidates instead of just voting for their top choice. If no candidate wins a majority, the candidate with the fewest first-choice votes is eliminated and his votes redistributed based on ballot rankings until someone wins a majority.

The process, also known as “ranked choice voting,” has been used in San Francisco, Burlington, Vt., Takoma Park, Md., Cary, N.C., and Pierce County, Wash.

Supervisor Mark Ridley-Thomas proposed that the county consider instant runoffs to combat “voter fatigue,” noting that by the end of May, residents in his 2nd District will have participated in six elections since January 2008. That included the March 24 special primary to fill the state Senate seat he vacated when he was elected supervisor in November; it cost the county registrar-recorder $2.2 million and saw voter turnout of just 6%.

“The costs are serious, and instant runoff voting is a more efficient way to expedite the voting process,” Ridley-Thomas said today.