How do you cross 2 railway lines, 3 canals and 2 rivers? Obviously not with one bridge. But this was the dilemma facing road builders in the 1950s and 1960s, especially the construction of new motorways in highly urbanised areas of major cities.

There is estimated to be about 9000 bridges on the network of 2,300 miles of UK motorway. This doesn’t take into account the 29500 miles of primary highways (A roads). These bridges aren’t pretty, they concrete slabs on concrete pillars, and are purely functionality and designed to last… Except 4000 are substandard due to age. The most complex of these bridges are found at motorway junctions (interchanges), and the most famous has to be the Spaghetti Junction in Birmingham – its actual designation is Gravelly Hill Interchange, junction 6 of the M6. It covers 30 acres, accessing 18 routes, 2.5 miles (4km) slip roads, but less than a mile of the motorway itself. Supported by 559 Columns, reaching up to 24 metres high, the total stretch of elevated motorway is 13.5 miles (21km). To look at, you can see why its called Spaghetti Junction, as it criss-crosses five different levels of roads.

The name came from a reporter, Roy Smith, who wrote in the Birmingham Evening mail on June 1st 1965, shortly after the Junction’s opening, “Cross between a plate of spaghetti and an un­successful attempt at a Staffordshire Knot.” The name spread around the world, and there are now numerous ‘spaghetti functions’.

As for what lies beneath the network of elevated roads, it is the tranquillity of rivers and canal. Having been on a canal boat underneath it, I can confirm it’s possible for a narrow boat to make better progress than the traffic above during rush hour. This intersection of old and new worlds was incorporated into the junction’s design. The pillars for the flyovers were located in such a way as to allow horse drawn boats to navigate under the junction without tangling the tow ropes.

So up and down the country, these bridges that play a key role in junctions number in their thousands, are challenging to maintain and repair, ugly, and hardly a giant legacy of modern transportation compared to suspension bridges or fancy footbridge designs, yet they are crucial to the flow of traffic. Since the responsibility for these bridges lies in the hands of government agencies, it will be the taxpayers who must pay for their maintenance. I wonder when the motorways were first constructed the planners quite realised the sheer volume of traffic that would use them 60 years on.