The Department for Transport (DfT) carries out a minor road traffic benchmarking exercise approximately every 10 years, with the aim to improve the accuracy of traffic estimates for minor roads.
Mae'r Adran Drafnidiaeth yn cynnal ymarfer meincnodi traffig ar gyfer is-ffyrdd bob rhyw 10 mlynedd, a'r nod yw gwella cywirdeb yr amcangyfrifon traffig ar gyfer is-ffyrdd.