The A4234 is a short link road through the disused Cardiff docks area. It is dual for its entire length.
The road starts by the prison on the A4160 Adam Street and heads south along the Central Link (which isn't particularly central to anything). There's a bridge over the Newport to Cardiff railway line and the unclassified Tyndall Street, after which slip roads from that road come up to meet us. Owing to the incomplete state of the A4232 that road is currently the signposted route from the M4 to Cardiff Bay even through it's mostly unclassified.
We continue along a straight road between a factory and the former Bute East Dock, now separated from the coast and surrounded by modern luxury buildings. A roundabout is soon reached which provides access to the dock and County Hall (home of South Glamorgan County Council until 1996 and Cardiff Council since then). A further short section of road leads to our terminus roundabout on the A4232. That road has not yet been built to the east so can only be travelled west, through the tunnel and over the River Taff. Other traffic can continue ahead along an unclassified road for Cardiff Bay and the docks.