The A48 (renumbered from the B22 in the mid-1920s) forms part of the principal road link from Belfast to the town of Donaghadee, via Newtownards. It is 2-lane single-carriageway standard for its entire distance.
Beginning at a roundabout on the main A21 Bangor Road in Newtownards it climbs steeply uphill to the summit before heading cross country towards Six Road Ends. This stretch of the road passes through drumlin country and there are hence a series of bends that restrict speed. Six Road Ends was a notoriously unsafe, busy rural junction where 6 roads met at a single priority junction. The junction was bypassed in 2007 by the construction of a new roundabout.
East of Six Road Ends the A48 passes through very flat agricultural land, with long stretches of perfectly straight road. We enter Donaghadee and reach a T-junction where we meet the B21 and TOTSO right to take on its original eastern end. The road ends in the town centre at a gyratory on the A2.