On Tue, 14 Oct 2014 17:15:16 -0700 (PDT), in rec.bicycles.tech
jbeattie wrote:

Query if flashers are legal under the UVC. I was looking at the Oregon statutes,
and flashers are prohibited on cars, and I didn't see any exception for bicycles --
although I didn't look closely. I've never seen anyone get a ticket, and flashers
on bikes are ubiquitous.

-- Jay Beattie.

Flashing lights other than turn signals are usually prohibited on
motor vehicles under normal driving conditions in most US states.
Some states (Colorado, for example) prohibit driving with parking
lights; however, I'm sure it's not rigidly enforced. Back in my
college days, I drove a taxicab; when I'd cruise for a fare, I'd turn
on my 4-way flashers. One night, I was pulled over and told to quit
doing that.

OTOH, I frequently see amber flashers on service vehicles like garbage
trucks.

Jones