There are 8 roads (9 different routes as the A40 is split into two sections) on the TERN route, 5 of which are in South-East Wales and 4 of which are in South-West Wales.
Rhennir ffyrdd A yn ‘gefnffyrdd A’ (rhan o rwydwaith ffyrdd strategol sy’n eiddo i’r llywodraeth ac yn cael ei rheoli ar ei rhan) a ‘ffyrdd sirol A’ (pob ffordd ‘A’ arall).