A58(M) and A64(M)

The Leeds Inner Ring Road is one motorway with two numbers, designated A58(M) from its western end to Claypit Lane and A64(M) from there to the eastern end.

The A64(M) part is very small, and was once a candidate for the title of Britain's shortest motorway, a battle it fought for many years with the equally inconsequential A308(M). Today Glasgow's A8(M) is considerably shorter than both, but neither can claim to be quite so uneven: the A64(M) is considerably longer eastbound than it is westbound.

The A64(M) is so confusingly lopsided because Woodpecker Junction, where the motorway terminates and becomes the A64, was meant to be something bigger. In the 1970s it was planned to be the point where the Inner Ring Road turned south to connect with some unfinished ends at junction 3 of the M621. This was never done; so what would have been a double-deck road structure only exists in one direction. Eastbound traffic goes on the top deck all the way, but westbound the motorway can't begin until the other half of the top deck appears.

The rest of the Inner Ring Road, in terms of engineering, is something of a masterpiece. It removes a massive amount of through traffic from the city streets without really being noticable at all. It runs almost entirely in a vertical-sided cutting, up to 20ft deep, with numerous short cut-and-cover tunnels. It hides the road and shields its noise so effectively that even when walking it's hard to tell you're anywhere near it until you find yourself on an overbridge looking down at four lanes of fast moving traffic.

At North Street, there's the unusual design feature of a right-hand exit sliproad when heading eastbound. Early plans of the route reveal that this was added to save space, the alternative being an exit slip around the outside of the current loop, which would have interfered with the merge from the A660. The same early plan showed the sliproads to the A61 at Claypit Lane on the inside of the junction, with the mainline passing around the outside - a pair of right-hand entry and exits, which thankfully were never built!

Finally, this was the UK's first ever urban motorway, opening shortly before Manchester's A57(M) Mancunian Way and beating more famous roads like Westway (originally a motorway but now part of the A40) by several years.