A30

The A30 is one of the UK's longest A-roads, running from the fringes of London to Land's End. But its true home is in Cornwall.

Along the way it varies in importance, beginning life as a suburban arterial road, connecting up a string of large Hampshire towns, and then quietly retreating into the background while the A303 takes the limelight from the M3 to Somerset. Then suddenly - and the transition is indeed very sudden - at Honiton it transforms into a major interurban expressway, powering across the middle of Devon and forming the vital spine road on which virtually the whole of Cornwall relies.

It's the expressway through Devon and Cornwall that puts it here in the Motorway Database, of course, and while the idea of a spine road down into the south west might seem obvious it's only surprisingly recently that it's formed anything like a continuous route. In fact the history of the A30 in the south west is a story of one bottleneck being replaced by another.

As far back as the 1930s the Exeter Bypass was a problem, and by the 1970s it was unbearable. Further down the line, the difficult bends at Launceston and the historic town centres on the rest of the road meant the journey from north of Exeter to the far reaches of Cornwall could easily take the best part of a day in summer holiday traffic. Even today, with most of the route a fast dual carriageway, the first rule of driving in Cornwall is that it's further than you think to Penzance.

In 1977, the new M5 Exeter Bypass opened, solving the most notorious bottleneck once and for all, just a year or so later than other vital bypasses at Redruth, Launceston and Bodmin. But all it did was move the bottlenecks to new places: with traffic moving freely on new roads, Exeter and Launceston were replaced by Okehampton and Indian Queens in traffic reports. New bypasses continued to open until the bottlenecks became the end of the bypass and the return to the old single carriageway road between them. Each generation's memories of childhood holidays to the south west are characterised by memories of the summer queues on the A30 at whichever was the worst part when they visited. (When I was a child it was the end of the Okehampton Bypass and the long slog towards Launceston, a rural stretch that was finally bypassed in 1993.)

Today the gaps in the expressway are closing. Cornwall Council themselves funded work to upgrade the section between Temple and Higher Carblake to bring an end to the crippling effect it was having on the county's economy. Now, a final section is needed to make it continuous.

In planning, and again to be funded by Cornwall Council, the gap between Carland Cross and Chiverton Cross will be plugged with a new dual carriageway. That will complete the continuous expressway from Exeter to Redruth and perhaps, for the very first time, put an end to the chronic congestion that has been a feature of summer holidays on the A30 since long before anyone can remember. It's almost certain to be followed by calls for the dual carriageway to be extended further, on from Redruth towards Penzance - work that was proposed in the early 1990s but scrapped long ago.

What we're left with, despite the one remaining gap, is one of the UK's most pleasant expressway routes, traversing varied scenery from the rolling hills of Devon to the stark expanse of Bodmin Moor and the cosy villages of Cornwall. It helps, of course, that many of its travellers associate it with summer journeys to the seaside and holidays in one of Britain's most wonderful regions. And even for those who don't - those who live in Cornwall all year round and use the A30 to get to work or to run their business - the shape and the geography of the county mean that there are few other dual carriageways that could claim to be quite so uniquely indispensable.