The former A4108 in Glyn Corrwg
The A4108 was a dead-end road in South Wales which ran north from the A4063 in Cymer up the valley to Glyncorrwg, where it ended just before the bridge crossing the Afon Corrwg, mountains on all sides preventing it from going any significant distance further.
In the original 1922 road classification scheme, it had been a Class II road numbered B4285 and gained the A4108 number in the mid-1920s. The road became an extension of the A4063 in 1935, when the A4107 took over the A4063's route west of Cymer. This allowed the A4108 number to be re-used, after 1945, for a a major road in North Wales which has since become a part of the A470.
The road is now unclassified.