2015 Cable Car bell ringing contest

Hundreds of people gather at Union Square for the 52nd Cable Car Bell Ringing Contest on Thursday, July 9, 2015. The contest is split into two categories. The first category featured amateurs who competed for charity. The second category featured the professional division where Muni operators compete for cash prizes. (Michael Ares/Special to the S.F. Examiner)

Muni operator, Bryan Cobb, holds up his first place trophy as he becomes the new Cable Car Bell Ringing Champion at Union Square on Thursday, July 9, 2015. (Michael Ares/Special to the S.F. Examiner)

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Muni operator, Bryan Cobb, holds up his first place trophy as he becomes the new Cable Car Bell Ringing Champion at Union Square on Thursday, July 9, 2015. (Michael Ares/Special to the S.F. Examiner)

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Behind the scenes at the Goldman Prize

Executive director talks about mission of awards, which are announced May 25