A465 and A40

By turns ruggedly beautiful and grittily industrial, the newly-completed A465 Heads of the Valleys Road might be one of the UK's most surprising and satisfying expressways.

Stretching east-west across the northern fringe of the densely-packed valleys of South Wales, the Heads of the Valleys Road picks its way between towns and industrial estates on one side and the wilderness of the Bannau Brycheiniog National Park on the other. 

Its surroundings give it a unique and pleasing variety: the varied terrain means it traverses plains and lush rolling countryside, open windswept moors and a dramatic wooded gorge, but the journey is never far from civilisation, punctuated by sights of heavy industry and encounters with commercial tin sheds and semi-detached suburbia.

The central part of the road was built, back in the 1960s, as a critical infrastructure project to link industrial centres in South Wales and the Midlands, a job it still does today - but its role now has grown to be far greater than that. Along with the M4, running east-west across the southern end of the Valleys, it is one of the key road links that ties South Wales together. Its upgrade to provide a complete expressway from the A449 at Raglan to the M4 at Neath makes it very nearly the equal of the M4, capable of taking the pressure off its southern counterpart and opening up the northern ends of the Valleys to new opportunities.

The upgrade was needed because the road built back in the 1960s was barely suitable even from day one. It was designed as a three-lane single carriageway, having one lane each way and a third free-for-all overtaking lane in the middle to be shared by traffic in both directions.

It took years to build - many years longer than intended - because of the difficult terrain and the number of bridges required. We have a whole article telling the story of the hard fight to build it. But even its opening brought little joy; despite the Ministry's repeated protestations, nobody thought a single carriageway was adequate and nobody thought the three-lane design was safe.

While the critics were largely proved right on both counts, it was to be another 30 years before the Heads of the Valleys got its second chance. Set out in the mid-1990s, the plan to convert it to a dual carriageway was supposed to be carried out at speed, but the difficulty of the engineering and cost of the work meant it would take several decades more. 21st century roadbuilders found themselves bogged down and held up by the same problems that had faced their predecessors 50 years before.

The expressway was finally completed in 2025, and it was worth the wait. The safety benefits of the new road are obvious and the economic benefits will be counted in years to come. But what's impossible to log in a spreadsheet is the marvel of engineering that has been created: South Wales has been blessed with one of the UK's most impressive and distinctive roads: not just a fast highway from A to B, but a delightful, inspiring journey through all the light, the shade and the glory of the Valleys.