Roedd yr astudiaeth yn ystyried yr effeithiau y byddai’r gwaith yn eu cael ar ardaloedd sy’n cael eu gwasanaethau gan yr A40 fel Hwlffordd, Aberdaugleddau ac Abergwaun a’r A477 fel Doc Penfro a chyrchfannau twristiaeth ar hyd arfordir y de.
The study considered impacts on areas currently served by the A40 such as Haverfordwest, Milford Haven and Fishguard and the A477 such as Pembroke Dock and the south-coast tourism destinations.