SEVEN hundred miles of motorway are being lost due to drivers' poor lane discipline.

The 'middle-lane hogs' and the 'outside-lane blockers' are wasting up to a third of motorway capacity in peak periods, according to research from the RAC Foundation.

Often, poor lane discipline leads to vehicles tailgating. Any slight incident, such as changing lanes or leaving the motorway, can force a tailgating motorist to hit the brakes hard. This can produce a brake light domino effect, with subsequent cars braking hard until they come to a standstill.

RAC executive director Edmund King said: "If we can encourage these drivers to practise better lane discipline it would be equivalent to adding 700 miles of new motorway capacity."