“The M4 is of vital importance to the Welsh economy and this maintenance to the Brynglas Tunnels forms part of our ongoing commitment to improving the motorway.
“Mae’r M4 yn bwysig iawn i economi Cymru ac mae’r gwaith o gynnal a chadw Twneli Brynglas yn rhan o’n hymrwymiad parhaus i wella’r draffordd.