Roeddy data, a gasglwyd gan Trafnidiaeth Cymru, yn monitro cyflymder miliynau o gerbydau mewn naw cymuned wahanol ledled Cymru cyn ac ar ôl i'r terfyn gael ei roi ar waith.
The data, which was collected by Transport for Wales, monitored millions of vehicles’ speeds in nine different communities across Wales before and after implementation.