Hypothetically at what price of gas would drivers consider using alternative transportation or would decide to drop driving?

Saw this asked on another subreddit. Personally, I think gas here in Oahu would have to reach at least $9 range. Where a driver might consider taking alternative transportation like bus, finding a job closer to home, etc. Anything higher. Well, I think we would be a big doozy. Considering gas is already around $6+ or near it.