A blue sign with a diagram showing a branch off the road ahead and the following text.
Forward destinations: SOUTH WALES; Bristol; Bath.
Exit destinations: Swindon (W); Royal Wootton; Bassett ; Calne; A3102.
Junction number: 16.
One thing the Simulator doesn't quite capture is the distance between junctions on a motorway like this. In the space of a few clicks we have clocked up some serious miles - Reading was just four junctions back, but it's now 40 miles away.