 They sport green Interstate shields, as opposed to the normal red and blue, with the word "Business" replacing the normal "Interstate" word on the upper portion of the shield.Truck routes were initially known as Bypass routes, and were loops created as a means to divert through truck traffic away from population centers, but the designation was changed to "bypass" in 1959-1960 by AASHTO.Today, Truck routes exist as alternatives for the mainline routes that are ill-suited for large truck travel with obstacles (such as low clearance bridges, sharp turns, or steep grades) or with conditions that could create dangerous situations to smaller vehicles.