Rule 143
One-way streets. Traffic MUST travel in the direction indicated by signs. Buses and/or cycles may have a contraflow lane. Choose the correct lane for your exit as soon as you can. Do not change lanes suddenly. Unless road signs or markings indicate otherwise, you should use the left-hand lane when going left the right-hand lane when going right the most appropriate lane when going straight ahead. Remember – traffic could be passing on both sides. Laws RTA 1988 sect 36 & RTRA sects 5 & 8