If you plan to walk from Tegfan to Cwm yr Eglwys, it will take you about 10 minutes along this road. Walkers don’t expect traffic here; they’ll be admiring the wild flowers in the hedgerows (more of that another time) or walking several abreast with their dogs along a road that has been reclassified as a path.
Where there is soil below, the grass is growing through the tarmac. Where there is no soil, the tarmac has worn away completely to reveal the rock underneath. The downward slope must be steeper than 25% where the road bends to take you to the houses at the bottom. If you really want to drive to Cwm yr Eglwys there is a proper road from the A 487.