Mae’r A465 yn rhan bwysig o’r rhwydwaith ffyrdd strategol ac o bwysigrwydd lleol, cenedlaethol a rhyngwladol.  Yr 18km o’r ffordd rhwng Dowlais Top, Merthyr Tudful a Hirwaun (Rhannau 5 & 6) yw’r rhannau gorllewinol o’r rhaglen ddeuoli ac ar hyn o bryd maent yn gerbytffordd sengl tair lôn gyda chyffyrdd un-lefel sy’n cyfyngu ar lif y traffig ac yn cael effaith ar ddibynadwyedd.  Mae gan y ffordd record diogelwch gwael, ychydig o gyfleoedd i oddiweddu a chyfleusterau teithio llesol gwael.
The A465 is a key part of the strategic road network and is of local, national and international importance. The 18km length between Dowlais Top, Merthyr Tydfil and Hirwaun (Sections 5 & 6) are the westernmost sections of the dualling programme and currently remain a single three-lane carriageway with at-grade junctions that restrict traffic flow and affect reliability. The road has a poor safety record, limited opportunities for overtaking and poor facilities for active travel.