The national default speed limit for such roads is currently 30mph, although local authorities can use traffic regulation orders to set another speed limit in appropriate cases.
Y terfyn cyflymder arferol ar gyfer ffyrdd o’r fath ar hyn o bryd yw 30mya, ond gall awdurdodau lleol ddefnyddio gorchmynion rheoleiddio traffig i osod terfyn cyflymder arall mewn achosion priodol.