arrow blue bright direction indication one way only direction pointing pointing back sign traffic traffic flow traffic sign white black care caution communicating communication crossing informing pedestrians reflective speed reduction street sign warning yellow circular directing directional indicator roundabout aliens avenue civilization crosspoint crosswalk europe flow germany green green man hamburg lights martian order semaphore streetlights traffic ligths urban zebra line city city traffic dark darkened directions early evening hazy lighting pedestrian bridge rain reflecting reflections road conditions road curve shining shiny Singapore street light traffic lights vehicles weather wet bypass cars CBD commute freeway highway main-road motor-cars motor-vehicles road road-rules road-vehicles speed traffic-flow traffic-lanes transport travel wide wide-road arrows divergent diverging law no-alternative only pointer signs specific splitting splitting-up street-sign traffic-sign turn turning two-way black-on-white gray grey left-turn vehicular wording curved give-way red triangle triangular appropriate behavior appropriate behaviour directive give way road sign rules safety one-way one-way-signs