black danger hexagon pictogram rail railway red security sign track transport yellow autumn Farewell forest hiding place leaf leave leaves mystery silence wood angles appearance architectural capping construction cover covered covering damage damaged dangers dark dirty discolored discoloured elements exterior external gap gaps hole holes lines missing old orange perspectives protection protective repair repairing roof roofing rooftop rows Somber sombre surface surfaces textures tiled tiles tiling uneven abstract aged angled asphalt background basic bitumen broken cracked cracks damaging dangerous debris deteriorated deterioration Dirt dry gray grey hard-surface poorly-maintained risk risky road rough split streaked streaks street surfaced tarmac texture advice alert appropriate-behavior appropriate-behaviour be-careful beware care careful caution communicating communication concern conditions directions garden garden-beds informing keep-out lookout not-allowed not-permitted planter-beds prohibited prohibition risks signs warning warning-sign watch-your-step