Question On low bridges: Answers Height warnings must always be posted. Height warnings must be posted at least twice. Height warnings may be posted, but do not have to be. Explanation Height warnings are often, but not always, posted on low bridges. If you are unsure if you will be able to clear an overhead object, go slowly. Take a FREE Practice Test Now This questions appears in the following tests: Arizona Knowledge Test Class A , Arkansas Knowledge Test Class A , Wyoming Knowledge Test Class A , Oklahoma Tank ,