Edge line

A solid white line along the side of the road marks the edge of the carriageway - where the part meant for traffic ends. It is on the left-hand side of the road, and beside the central reservation of a dual carriageway, and it is especially useful at night and in poor visibility for showing where the road goes. It is broken where a side road, private drive or lay-by joins. On motorways and some roads with a hard shoulder it has raised ribs, which rumble if your tyres run over it.