Between Machynlleth and Dolgellau with Cadair Idris in view
|Length:||174 mi (280 km)|
| A4076 road
The road starts at a junction with the A40 in Haverfordwest, from where it travels north-west to St David's, then switches north-east through Fishguard, Cardigan, Aberaeron, Aberystwyth, Machynlleth and Corris.
Through the town of Fishguard, the road width in places is a very narrow single lane, leading to many traffic issues, especially with HGVs. As of 2010[update], articulated HGVs have been banned from a section between Fishguard and Dinas Cross because of this.
The road continues to Dolgellau multiplexing with the A470 north of the Cross Foxes inn. After Dolgellau, the road continues to multiplex with the A470, re-emerging just north of Trawsfynydd then passing through Penrhyndeudraeth and Porthmadog. The road terminates at the foot of the Menai Suspension Bridge near Bangor.
The section of road in the Dulas valley between the Afon Dyfi near Machynlleth and Corris was built in the 1840s at the instigation of the local slate quarry owners to replace the old turnpike road on the opposite side of the valley. It may have utilised part of the formation of the Roman Sarn Helen. From 1859 the road was kept company on this section by the narrow-gauge Corris Railway.
The site of Dolgellau railway station along with approximately a mile and a half of trackbed of the former Great Western Railway line from Ruabon to Barmouth was used to construct the Dolgellau bypass in the late 1970s.
Between Penrhyndeudraeth and Porthmadog, the road passed over a mile-long embankment, known as The Cob. Until 2003, drivers had to pay a charge to cross The Cob. In 2008 the Welsh Assembly Government published plans for the Porthmadog, Minffordd and Tremadog bypass, which would reduce the amount of through traffic in the town. Work started on the project in 2010, the route of which passes under the Ffestiniog Railway, and then crosses over the Welsh Highland Railway. The original route over The Cob was renumbered as the A4971.
The section between Porthmadog and Llanwnda has been improved. The new section bypasses Llanllyfni and Penygroes, in parts utilizing the old trackbed of the Caernarfon to Afon Wen railway line. In April 2007, the 10-mile new section had to be resurfaced in its entirety after it became apparent that the wrong type of stone had been used for the surface tarmac.
It is proposed to build a further bypass to avoid Caernarfon (from the northern end of the Pen-y-groes bypass to the western end of the Y Felinheli bypass) thereafter, with construction due to begin in 2015.
- "Directions to Treborth Rd/A487". Google. Retrieved 14 April 2013.
- Assembly abolishes toll on Porthmadog Cob at Welsh Government website, 28 March 2003. Retrieved 2012-10-21.
- Welsh Assembly Government : A487 Porthmadog, Minffordd and Tremadog Bypass
- "Road closure for new aerial bat crossing". BBC News. 30 January 2010. Retrieved 5 June 2011.
- Williams, Gareth (5 July 2012). "‘Purple route’ for £100m Caernarfon bypass". Trinity Mirror North West & North Wales Limited. Retrieved 14 April 2013.