villages are at the southwest end of and . Transport Roads Six primary routes serve Snowdonia, the busiest of which is the A55, a dual carriageway which runs along the north coast and provides strategic road access to the northern part of the national park. The most important north–south route within the park is the A470 running from the A55 south past to to . It exits the park a few miles to the southeast near . From , the A494 runs to whilst the A487 connects with . The A487 loops around the northwest of the park from via to before turning in land to meet the A470 east of . The A5 was built as a mail coach road by Thomas Telford between London and Holyhead; it enters the park near and leaves it near Bethesda. Other A class roads provide more local links; the A493 down the Dovey valley from and up the coast to then back up the valley to , the A496 from down the north side of the to Barmouth then north up the coast via to . The A4212 connecting with is relatively modern having been laid out in the 1960s in connection with the construction of . Three further roads thread their often twisting and narrow way through the northern mountains; A4085 links with , the A4086 links with via and the A498 links with the A4086 at . Other roads of note include that from up to via the 545 metre (1788') high pass of , the second highest tarmacked public road in Wales and the minor road running northwest and west from towards via the 531 metre (1742') high pass of . Railways The double track North Wales Coast Line passes along the northern boundary of the park between Conwy and Bangor briefly entering it at Point where it is in tunnel. Stations serve the communities of Conwy, Penmaenmawr, Llanfairfechan and Bangor. The single-track Conwy Valley Line runs south from Llandudno Junction, entering the park north of Betws-y-coed which is served by a station then west up the Lledr valley by way of further stations at Pont-y-pant, Dolwyddelan and Roman Bridge. After passing through a tunnel the passenger line now terminates at Blaenau Ffestiniog railway station. Prior to 1961 the route continued as the Bala and Ffestiniog Railway via Trawsfynydd to Bala joining another former route along the Dee valley