Honolulu is weighing whether to sell ad space on the outside of its trains and buses, a small money boost for a transit system that loses hundreds of millions a year.

• Bill 59 would lift the ban on ads on the outside of city transit vehicles, which could bring in $6 million or more a year.
• Honolulu spends $475 million a year running transit and takes in only $50 million, so the gap is wide.
• Ads inside the vehicles are already allowed but raise almost nothing by comparison.
• Political ads, obscene content, and anything off-limits to kids would be banned, and council members want strict rules written before the bill moves ahead.
• Some riders object to covering up Skyline's rainbow design, which they see as part of Hawaii's look.

Outlook: The bill advances only after transit officials and the council agree on ad guidelines, as Skyline ridership hits new highs with students back in school.