This sign reminds me of one that is being used by our local downtown association. Essentially - this sign warns of a bridge out. It's there - you just have to look closely.
It's not a good idea to make your customers try to figure out the message in whatever you're showing them. When you are working to convey a message make sure that message is absolutely clear and at the forefront.
While you care deeply about your message, your customers don't until you've "hooked" them. A sign like this certainly would do that but you won't really get the critical message to the customer.