authorised danger restricted risk sign warning attention beware blue careful caution child conduct control course drive guide happen highway industry kids law limit Look pedestrian pedestrians people playground playing protection respect road school sidewalk slow street symbol teen traffic transportation walk way zone Dirt grasses leaves spider stems yellow ash boiling brown Dead trees gray hot springs mountains orange water white yellowstone green hot mountain pine trees bushes clouds fire forest grass lookout metal silver sky summer tower watch Wildfires boardwalk Tan trees Australian edges flora foliage leaf leafed light pain Prickly protective shrubs spikes spiky spines texture textures thick alert animal animals announcement be careful black camel camels car care cars communicating communication driving informing mammal observant observe reflective safety security vehicles watch out access-denied advice appropriate-behavior appropriate-behaviour avoid concern damage dangerous demolition denied destruction directions fence fencing keep-out mesh message no-access no-entry not-allowed not-permitted permission-denied prohibited prohibition red risks risky unwanted warning sign weathered wire-mesh