"Mae hynny wedi arwain at sefyllfa lle nad oes gan drenau ddewis ond teithio'n araf ar Brif Reilffordd De Cymru, at gyfyngiadau ar gapasiti ac ar gyflymder ar hyd llinell Arfordir Gogledd Cymru, prinder gwasanaethau i gymudwyr yn ninas-ranbarth Bae Abertawe, a gwasanaethau trawsffiniol annigonol yng Ngogledd ac yn Ne Cymru.
“This has resulted in low lines speed on the South Wales Mainline, capacity and speed constraints along the North Wales Coast, infrequent commuter services for the Swansea Bay city region, and inadequate cross-border services in both North and South Wales.