A gantry spanning the motorway with blue overhead signs indicating one lane exiting and two continuing ahead, and the following text.
Left lane destinations: Caerdydd (G); Cardiff (N); Merthyr Tudful; Merthyr Tydfil; A470.
Right-hand two lanes destinations: Caerdydd (Gn); Cardiff (W) Pen-y-bont; Bridgend M4 .
Junction number: 32.
We're about to meet the A470, the spine road connecting Cardiff to the north coast of Wales, at a three-level junction that incorporates one of the world's most ludicrously enormous roundabouts.