This does not mean an end to road building, but it does require a higher bar is met, taking account of our climate and economic responsibilities.
Nid yw hyn yn golygu rhoi terfyn ar adeiladu ffyrdd, ond mae'n gosod meini prawf uwch y mae angen eu bodloni, gan ystyried ein cyfrifoldebau economaidd ac o ran yr hinsawdd.