It will be known as Measure T.
In essence, Measure T offers voters the chance to change the San Mateo County Local Coastal Program to require that any permanent repair of Devil's Slide be done either as a tunnel or as a repair of the current roadway. If approved, it would kill Caltrans' plan of record for cutting and filling across the mountain to build a 4.5 mile roadway.
The full wording of the initiative is here, and is worth reading over. It's only about 1000 words.
Tunnel backers announce initiative drive to change county's General Plan.
Initiative drive was months in the planning; kicked off in high style.