They say you can't regulate rudeness, but BART is determined to try.

In a 5-4 vote Thursday, the BART board of directors approved an ordinance that would fine "seat hogs" who wantonly take up more than their fair share of space. Now those rude riders will be subject to more than just side-eye from their fellow passengers. Violators will first get a warning before facing a $100 fine, $200 on the next offense and up to $500 for each ticket after that.

The ordinance will be enforced only from 6 a.m. to 10 a.m. and from 3 p.m. to 7:30 p.m. And people with medical or physical conditions that require them to occupy more than one seat will be exempt from the law.

There will be a six-month delay before the seat hog rule goes into effect as an education campaign rolls out to first let riders know their boorish behavior will be punished. That time will also be used to explore whether disabled and senior seating will be added to the "one ticket, one seat" policy.

"People pay a lot of money for a seat, and to be required to stand up while someone is taking more than one seat is really hard for people," said board member Joel Keller, who brought forward the proposal. Keller said most riders are courteous enough not to occupy two seats on a crowded train, but now officers will have authority to ticket those who refuse to move.