A fine-tuned policy to guide BART on when it should shut down cell phone service in its transit stations will be up for approval on Thursday.

The transit agency attracted international criticism in August when it opted to shut down cellphone service in its San Francisco stations to prevent a planned protest. In October, the agency’s board of directors was set to vote on an official policy to determine, when, if ever, cellphone service should be scrambled, but that action was delayed because some directors had concerns about the resolution’s wording.

On Thursday, the agency’s board will vote on an updated cellphone policy. The latest resolution adds language about BART’s primary mission — to provide safe, efficient and reliable service — and a line that states any cell phone interruption should be reported promptly to BART’s board of directors.

The agency’s board has already agreed to informal guidelines that BART should only shut down cellphone service in the case of “9/11”-type events.

wreisman@sfexaminer.com