Monktonhead Roundabout

Monktonhead Roundabout is very nearly the southern end of the A78. After many miles of largely grade separated dual carriageway, the road suddenly reaches a flat roundabout and turns sharply eastwards to meet the A77. The reason behind the lack of grade separation may well be that traffic volumes were once projected to be fairly equal on the A77 and the A79, which heads west then south to Prestwick Airport, and on into Ayr. The alternative, therefore, would have been an expensive Directional T junction design, or Trumpet Interchange, requiring a number of bridges and a much larger land take.

Despite not being grade separated, the junction is not signalised, and seems to cope reasonably well with traffic levels, although this may have been helped by the decline in flights from Prestwick Airport in recent years. There are actually four arms to the roundabout, the A78 turns between the northern and eastern arms, whilst the A79 heads west, all three routes being dual carriageway. To the south, the old line of the A78 still heads into Monkton, where it meets the old line of the A77. The onward route, however, is cut by the airports runway, hence the A79 now heads west initially around the airport.

A short distance to the west along the A79, a simple T junction, with central reservation gap, marks the southern end of the B749 which runs north to Troon. Prior to the A78 being dualled, this B road actually met the A78 at the site of the current roundabout, and it is not entirely clear why the route was foreshortened to meet the A79 at what is now considered to be a substandard junction, when it could have been plugged into the roundabout by simply buying a small additional piece of field.

Routes

Route	To	Notes
A78	Ayr, Kilmarnock, Glasgow (A77)
A78	Irvine, Greenock
A79	Prestwick Airport, Troon (A749)
B749	Troon	Meets A79 to west of Roundabout. Formerly met A78 at site of roundabout.
	Monkton	Former A78