Dewiswyd wyth ardal treialu i benderfynu ar y ffordd orau o weithredu 20mya ledled Cymru ac i sefydlu monitro hirdymor ar gyfer y newid. Rydym yn parhau  i gasglu data cyn y cyflwyno cenedlaethol a heddiw rydym wedi cyhoeddi'rAdroddiad Monitro Dros Dro. Mae hwn yn ddata cynnar iawn, fodd bynnag, mae'n galonogol iawn gweld:Ar gyfartaledd, bod modurwyr yn gyrru'n arafach ym mhob un o'r ardaloedd treialu;Ychydig iawn o effaith a fu ar amseroedd teithio a;Roedd cynnydd mewn teithio llesol yn fwy mewn ysgolion o fewn yr wyth cymuned o gymharu ag ysgolion eraill a gafodd eu monitro.
Eight trial areas were chosen to determine how best to undertake the 20mph implementation across Wales and to set up long term monitoring for the change. We are continuing to gather data before the national implementation and today we have published theinterim monitoring reportfrom these areas. This is very early data however, it is extremely encouraging to see that:On average, motorists are driving slower in all of the trial areas;There has been minimal impact on journey times and;Active travel increases were greater in schools within the eight communities than compared to other schools monitored.