The A4226 (better known as The Five Mile Lane) is a main road linking Bonvilston to Barry and Cardiff International Airport (CIA) in the Vale of Glamorgan, Wales.

The A4226 begins at the junction with the A48 road (Sycamore Cross) just east of Bonvilston and south of Gwern-y-Steeple and Peterston-Super-Ely.

It heads in a southerly direction past numerous farms and country lanes leading off to hamlets such as Llancadle, Moulton, Walterston and Dyffryn Gardens etc., past the Welsh Hawking Centre until the junction with Port Road (leading to the A4050 road at Colcot roundabout) at Weycock Cross in northwestern Barry.

However, the A4226 route forks some 120 degrees at Weycock Cross to the right as one approaches the roundabout, where it continues in a westerly direction (continuation of Port Road West) along the northern perimeter of the airport until the entrance to the airport at the Tredogan roundabout.

The improvements include adding straighter sections and other works to increase speeds along the road, and to extend the route designation to include the road between Sycamore Cross and the M4 Motorway Junction 34 (Miskin).