Simple and visible

IceAlert sign, New Westminster, BC

I saw this sign in parking lot near the Amazon warehouse in New Westminster. When the temperature gets to freezing blue wedges are displayed on the sign.

Three stages of IceAlert sign.
Source: http://www.icealert.com

These signs are a simple way of alerting drivers, and pedestrians, of potentially slippery conditions. Today many vehicles provide similar feedback, but these signs are a good additional warning. Of course the problem is that most people do not have idea idea that these signs exist or what the blue wedges mean. On first glance I though it was a variation on the nuclear fallout shelter sign.

Fallout Shelter sign
Source: https://upload.wikimedia.org/wikipedia/commons/thumb/c/cc/United_States_of_America_Fallout_shelter_sign.jpg/1200px-United_States_of_America_Fallout_shelter_sign.jpg

Still about falling, but the yellow and black sign is about radiation from the sky, the IceAlert one is about your backside hitting a frozen sidewalk.