Scotland's busiest motorways.The accident caused two lanes to be closed on the southbound carriageway just after the Kier Roundabout at junction 11 on the M9 shortly before 4.00 pm on Friday.Traffic ground to a halt with motorists forced to get by on the hard shoulder in the chaos with lines of cars queuing back onto the A9 at Dunblane.An image from the scene shows a large pile of wood lying in the middle of a lane on the road.A tweet from Traffic Scotland reads: "#M9 southbound just after the