Motorists using the M90 in Scotland will face the country’s first variable speed limits in three weeks time when a new traffic control system is launched on the road north of the Forth Road Bridge. The intelligent transport system, which goes live on 4 December on the M90 northbound, has been installed as part of construction of the Forth Replacement Crossing, which is due to open in four years time. Speeds will be automatically lowered by traffic sensors under the road surface when they detect congestion,