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.
The location of the Welsh Highland Railway's trackbed, its crossing point with the A487 Porthmadog Bypass, and the surrounding area are all described in this passage.