Red Smiddy Roundabout lies at the junction of the A8 and the A726 to the south of Erskine. The A8 here follows the 'new' Greenock Road, the Old Greenock Road running further north, although the new road is Victorian, if not earlier. For centuries, the route of the A726 was one of the main approaches to the ferry at Erskine Ferry across the Clyde, and still today the A726 to the north leads to the Erskine Bridge. However, with the coming of the M8 and M898 / A898 the importance of the A726 has diminished in long distance terms. It is still, however, the main route through Erskine, and connects to Paisley to the south.
The roundabout then is a simple 4 arm junction on the site of a former crossroads. The A8 passes through from east to west, and the A726 from south to north. With the exception of the northern arm of the A726, all of the approaches have been deflected from their original lines, although the hedgelines still show the rough outline of the old crossroads. They also suggest that the older roundabout lay slightly to the north east of the modern one. The junction was rebuilt in c2005, with three of the four approaches widened to 3 lanes - the western A8 only having two. This seems to have been related to the growth of the Inchinnan Industrial Estate to the south east, which presumably generates a lot of traffic on the junction.