Honolulu Rail: Ads or Graffiti?

It’s only a matter of time before these clean canvases presented by the massive pillars of the Honolulu Rail Transit system become targets for graffiti or advertisements.

rail-pillars

I’m hoping not but just too tempting being so big and so clean. Wonder what the ideas are to prevent defacement? Something better than the long gone decorative fence liners of Kamehameha Highway.