The road measures 32.27 miles long and would take a car obeying speed limits 55 minutes to travel its length.
The A478 is a A Road and is located in the Zone 4 Highways Region.
This is a true long-distance route, journeying through numerous towns like TENBY, New Hedges, Twycross, SAUNDERSFOOT, Moreton, KILGETTY, Pentlepoir, Begelly, Templeton, Providence Hill, NARBERTH, CLYNDERWEN, Grondre, Llandissilio, Efailwen, Hebron, Glandwr, CRYMYCH, Blaenffos, BONCATH, Rhoshill, Bridell, Penybryn, and CARDIGAN.
The road is located entirely within Dyfed.