Traffic Joins From Left Post Mounted Sign - Diagram 508.1 R2/RA2This sign is used to give a warning where there is traffic joining from the left hand side onto the main carriageway. This keeps the dual carriageway users alert and ready to move and allow new vehicles onto the road. Without this sign, cars may not notice the junction which could lead to sudden changes in speed and road position which can cause collisions or traffic build up. This sign should be positioned on the left of the main carriageway and is