background clay construction Dirt earth ground Mud relief surface texture track tracks tread instructions no entry prohibit restrictions rules safety sign signage signs sky stop transport emergency high hydraulic ladder long metal platform rescue rungs tall top horse horse-drawn carriage indonesia indonesian transportation pajajaran kingdom sundanese transportation west java province anti aircraft army detection electromagnetic equipment germany military peace radar Riese security war waves Wurzburg antenne advice alert announcement appropriate-behavior appropriate-behaviour be-careful beware black care careful caution communicating communication concern danger dangerous directions informing Look looking lookout observant red risk risks warning warning-sign watch watch-out white