|Length||14.8 mi (23.8 km)|
At Pen-y-Gwryd, the A4086 Llanberis Pass route bears off to the north. The A498 descends from a 277 m (909 ft.) summit at Pen-y-Gwryd and runs south west through the village of Beddgelert and the Aberglaslyn Pass, where it overlaps the A4085. The A498 then passes through Tremadog, overlapping the A487 for a short length before passing under the Cambrian Coast railway and terminating at Penamser on the A497 ( about a mile west of Porthmadog. At its northern end, the road forms a link via the A4086 with the ),A5 at Capel Curig, forming a useful holiday route to the Beddgelert/Porthmadog area. At the junctions, the A4086 to Llanberis is the minor road at Pen-y-Gwryd, while the A498 is the minor road at Beddgelert. At Pont Aberglaslyn, the A4085 is the minor road diverging to Penrhyndeudraeth and at Tremadog, the A498 is the major road. The junction west of Tremadog is a roundabout and at Penamser, the A498 is the minor road.
There is a steep descent of Nantgwynant and some 1¾ miles of this is on a substandard, narrow twisting alignment, where larger vehicles have difficulty in passing. There are further substandard sections in the Aberglaslyn Pass and towards Tremadog and coaches have had difficulty passing in this section. The road passes through Beddgelert by way of a sharp right angled bend over a river bridge, not recommended for articulated vehicles. In the Aberglaslyn Pass the trackbed of the Welsh Highland Railway, now being reconstructed, can be seen on the opposite side of the Afon Glaslyn. At its west end, the route crosses the new A487 Porthmadog Bypass at a roundabout west of Tremadog.
In late 2008 the Bryn-y-felin road bridge was rebuilt under the Welsh Highland Railway as part of Gwynedd Council's WHR Bridges policy. Unfortunately the bridge was rebuilt without a footpath and of such narrow dimensions that any vehicles wider than a standard car find it difficult to pass. It also has a 14' 9" height restriction.
The road was created from early toll roads. There was some improvement in the 1960s/70s in Nantgwynant and south of the Aberglaslyn Pass. Just south of the Goat Hotel in Beddgelert is an arched railway overbridge (with height and width restrictions) built by the Portmadoc, Beddgelert and South Snowdon Railway but never used.