Once upon an audit, there was a facility that didn't have signs to prevent visitors from entering restricted areas.
A lack of proper signage can lead to a policy violation, such as bringing a weapon on the premises, unlawful trespassers, etc. Proper signage is essential to ensure that established rules and regulations are followed. Signs indicating no trespassing, vehicles are subject to search, etc., need to be placed strategically around the facility. This includes all sides of the facility and at every parking lot and building entry. Be sure to place the signs in designated employee and contractor parking areas once they are established.
Bonus tip: Outdoor signage should be checked periodically for wear and tear, especially in the areas where inclement weather is a factor.