A wnaiff y Gweinidog egluro pam nad yw stoc drenau newydd yn cael ei chyflwyno ar reilffordd Treherbert ym mis Chwefror o gofio bod a) y rheilffordd i fod i ailagor fis nesaf, a b) bod y signalau wedi'u diweddaru a'r seilwaith trydaneiddio ar gyfer y trenau metro newydd wedi'u gosod ar hyd y rhan fwyaf o'r rheilffordd?
The deployment of rolling stock is an operational decision made by Transport for Wales.
The new electric trains need to be tested on the line before introduction into passenger service. This will be done over the coming months alongside necessary driver and conductor training. In the meantime, Transport for Wales will use the existing fleet to allow the resumption of services, and to familiarise train crew with the changes to signalling, track, and platforms.