City traffic - "For passengers, mainly rely on red, yellow, green bus three lines. The red line mainly goes around Queens Street and is a free bus. The yellow line is the outer ring line (S$1.8-3.4). The green line is the inner ring line (S$1.8). Lines at airports and Britomart transport centres, three lines will report to the station, you can also tell the driver where you want to go, arrival will remind you.