Mae Llywodraeth Cymru a Thrafnidiaeth Cymru yn gweithio mewn partneriaeth â Chynghorau Sir Gaerfyrddin, Castell-nedd Port Talbot, Sir Benfro ac Abertawe i ddatblygu cynigion ar gyfer Metro Bae Abertawe a Gorllewin Cymru.
Welsh Government and Transport for Wales (TfW) are working in partnership with Carmarthenshire, Neath Port Talbot, Pembrokeshire and Swansea councils to develop proposals for the Swansea Bay and west Wales Metro.