what where the odd poles with green circles on top we saw in Oahu?
November 28, 2009 11:13 AM   Subscribe

While on vacation at the north shore of Oahu we kept seeing these poles that had a number of green circle things on top, sometimes four of them but up to seven. The pole also had an antenna and a solar panel attached to it. What are these for?
posted by zeoslap to Travel & Transportation around Oahu, HI (6 answers total) 1 user marked this as a favorite
Best answer: Tsunami sirens?
posted by The Light Fantastic at 11:14 AM on November 28, 2009

Response by poster: It didn't really look like a siren but it is possible, we did see other poles with sirens on them though. It also doesn't explain why they had varying numbers of these circles/discs on top.
posted by zeoslap at 11:19 AM on November 28, 2009

Response by poster: GIS for tsunami siren reveals that you got it :) Now I can go read up on why they look so odd. Thanks.
posted by zeoslap at 11:21 AM on November 28, 2009

my vote is for tsunami sirens. they've been replacing the old ones with solar powered sirens. I don't think I've seen any of the new sirens, so I'm not sure if they're circular and green, but that's my guess.
posted by lex mercatoria at 11:24 AM on November 28, 2009

Response by poster: For anyone that's interested... this is the kind of siren we saw
posted by zeoslap at 11:27 AM on November 28, 2009 [1 favorite]

Yep. Each one of those circle things contains loudspeakers (aka "drivers") and the reason they're shaped that way is that the drivers reflect off of the housing above and below to radiate the sound in an omnidirectional pattern.
posted by SpecialK at 6:14 PM on November 28, 2009

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