|To:||Rhyd Ddu (SH569529)|
|Length:||7.5 miles (12.1 km)|
|Route outline (key)|
The B4418 is a largely rural road in central Caernarfonshire.
The route starts at a roundabout on the A487 Penygroes bypass, heading east for a short distance to the next roundabout on the old main road (former A4085) where it turns left and runs for less than half a mile into the centre of town. Here the B4418 TOTSOs right into Heol Buddug / Victoria Street and, after merging with Ffordd y Sir / County Road, heads eastward out of town.
For a mile or so after leaving Penygroes there are two roads running parallel. The one on the left, now serving local traffic needs only, was the original route of the B4418. Today, however, our route follows the bed of the old railway line as far as a T-junction in Talysarn where we come to a T-junction and turn right.
The B4418 now skirts the south side of an area of disused and flooded quarries together with their associated tips, on a by-pass route constructed in the mid-1930s, the original line of the road having been largely destroyed by these workings. The result is that today we enter Nantlle from the south, rather than the west, with the B4418 curving right to resume its overall eastward direction.
Until 1935 Nantlle was the terminus of the route but in that year it was extended eastwards to meet the next classified road (which at that time was a former route of the A487 and is today the A4085), some four miles further east. After passing the north side of Llyn Nantlle Uchaf the (frequently very narrow) road ascends the valley of Afon Drws-y-coed and crosses the mountain pass at Bwlchgylfin before passing the south side of the Llyn y Dywarchen reservoir before descending to Rhyd Ddu where it meets the aforementioned A4085 at a T-junction.