A group of blind voters is suing Alameda County in federal court, arguing that malfunctioning voting machines have interfered with their right to a private and independent vote.

The county has machines with audio and tactile features that allow blind and visually impaired voters to vote without having to dictate their ballot choices to strangers. But not all of those machines were working or staffed properly during the November election, said disability rights advocates who filed the class-action lawsuit Thursday in U.S. District Court in San Francisco.

"It's extremely frustrating," said Union City voter Lisamaria Martinez, who is blind and one of five named plaintiffs. "It's an American tradition to vote independently."

Martinez said she spent hours trying to vote in November after problems at her Union City precinct forced her to walk to another polling center. Uncomfortable with relaying her political picks to strangers, the 32-year-old eventually decided to wait for her husband to return from work.

The civil rights lawsuit seeks to compel Alameda County to make sure the machines are working and to train poll workers to set them up properly. The Alameda County Registrar of Voters, which is responsible for running elections, did not return calls for comment.

There is "no excuse in terms of a lack of a technological solution," since the machines for visually impaired voters are readily available here and around the country, said lawyer Stuart Seaborn of the Disability Rights Advocates, a nonprofit legal center in Berkeley that is representing the five voters and the California Council of the Blind on the case.

Blind voters "don't want to have to share who they vote for with someone else, especially if they go by themselves. It's a bit of a chilling effect," Seaborn said.