A55

One of the most important roads in Wales, the A55 is second only to the M4, providing a lifeline to the densely populated North Wales coast and connecting the port of Holyhead to the trunk road network across the English border.

Until relatively recently Holyhead was a remote and difficult place to reach. The A5 formed the better road out there and negotiating the coast road was a day out in itself, passing through the sort of geography that surpasses the word 'rugged'.

The worst point was always that around Penmaenmawr, where the A55 negotiated several tricky headlands (only made truly motorable in the 1930s with extensive rock-cutting) and passed through Conwy itself, meaning a crawl along single-file streets and several passes through the town walls. Crossing the Menai Strait to Anglesey was by Telford's Menai Bridge, all but impassable by goods vehicles.

Extensive improvements since then have provided a fast dual carriageway route, almost entirely grade-separated, from the M53 at Chester right up to the port at Holyhead. In the early 1980s the worst part was finally alleviated with the construction of a new urban route bypassing Colyn Bay and Conwy, with a tunnel under the river to avoid Conwy's town centre, narrow bridge and castle.

The two headlands either side of Penmaenmawr have been improved with new tunnels westbound, leaving the 1930s cliffside route for eastbound traffic. And access to Anglesey was made simpler, first with a new crossing provided when the Britannia Bridge was rebuilt following fire damage, and then in 2001 with the opening of about 25 miles of new expressway from the Menai Strait to Holyhead.

The Colwyn Bay section is particularly interesting because it is a very rare "secret motorway". It was built using special road powers, the same legal orders used to create a motorway, but was never declared as one. This creates the unusual situation where it is not a public right of way and not a motorway, and therefore the National Speed Limit does not apply to it. Motorists driving through from the NSL sections on either side will see a 70mph sign, and at the end, another NSL sign - yet the speeds permitted are no different along the entire stretch. It's made even more strange by the fact that it was built in two sections, and the point where one ends and the next begins is marked with another 70mph sign, ending the previous limit and starting a new, identical one.

Legal anomalies aside, the result of the hard work put in by engineers since the 1930s is one of the most spectacular high-speed roads in the UK, as varied and unique as it is picturesque.