The Welsh Government will also take into consideration any planned improvements or changes on the route during the life of the project as these might have a bearing on the mileage concerned.
Bydd Llywodraeth Cymru hefyd yn ystyried unrhyw welliannau neu newidiadau arfaethedig ar y llwybr yn ystod oes y prosiect gan y gallai'r rhai effeithio ar y milltiroedd dan sylw.