against circle letter mail mails many pictogram prohibition protest red road roadsign sign signs spam spammed stop warning bare barefoot foot no shoe shoes wear advice alert announcement appropriate-behavior appropriate-behaviour be-careful beware care careful carpark caution communicating communication concern danger dangerous directions informing Look looking lookout observant pedestrian pedestrian-speed reflective risk risks safety shared-area slow slow-down speed traffic warning-sign watch watch-out white behave behavior behaviour black communicate information large-vehicles limitations limited restricted restriction restrictions reversal reversing risky trucks vehicles attention germany isolated uneven road circles denied disapproval disapproved inform message messages not-allowed not-permitted permission-denied pictograms prohibited prohibitions protect protection public rules signage symbols don't go past this sign forbidden not beyond this point pedestrians stop here traffic sign advising be-prepared-to-stop cars hazard limited-access motorcars no-overtaking no-passing readiness ready road-sign roadwork workers workmen cycling incline slope steep track safeguard security theft risk