The extension of the motorway through to the roundabout at Newbridge completed the early phase of the motorway in the east.
J4 for the A801 is the first landmark, with a new high quality single carriageway road through to the M9 at its Junction 4. Sadly, the A801 still has about a mile missing - over the Avon Gorge.
J3a was an addition to serve the western expansion of Livingston, and the eastern area of Bathgate.
J3 for Livingston
J2 for Newbridge
The 1971 construction terminated at a roundabout on the A8, with the M9 starting on the far side. The extension to Edinburgh was completed in the mid-1990s, and grade separation of the Newbridge Roundabout shortly afterwards.