Two numbers, one road. The main road south from Glasgow, and indeed most of Scotland thanks to its connections with the M73 and A702, is having something of an identity crisis.
In the 1960s, most of the A74 from Gretna to Glasgow was upgraded to dual carriageway - a relatively simple job becaise it passed through vast swathes of remote country, and running a second carriageway alongside the first wasn't a problem. Near the northern end the route begins to see some larger towns, and this part was bypassed by the M74. By the early 1990s, the dual carriageway - with all its nasty right turns, sharp corners and steep hills - was becoming dangerous and overloaded. A considerable amount of money was spent, over the course of the decade, on replacing sixty miles of road with a new motorway, which was open by the early 1990s.
North of junction 13, this new motorway was mostly built on a new alignment, and was called the M74. South of there, the road was mostly upgraded from the old dual carriageway, with a service road built alongside for non-motorway traffic, and was called the A74(M). Giving an upgraded A-road a number like this is not unusual, but making a road arbitrarily change its number half way along certainly is.
The M74 has been the source of a great deal of controversy. At its northern end, in Glasgow, the last few miles that bring the motorway to its terminus on the M8 are an elevated urban motorway that was, astonishingly, built in the early 21st century and opened in 2011. This sort of project just doesn't happen in this country, and the legal and political wrangling involved to get it off the ground was nothing short of epic.
At its southern end (or, strictly, the southern end of the A74(M)), the route is a continuous motorway right down to the M1 at Rugby, thanks to the M6. When the Scottish part of the motorway was built, the new signs were manufactured with "A74(M)" and "M74" on stuck-on plates, and it is known that if these were removed it would read "M6" underneath. Originally it was proposed that it would be renumbered once the motorway was connected to the M6, but the two were linked in 2008 and no change in number ever happened. The Scottish Government are now very evasive about the whole issue, not actually ruling out the idea of ever extending the M6 into Scotland, but certainly making it clear that there's no current plan to do it.
Aside from its current peculiar number, the M74 is one of Scotland's oldest and most interesting motorways. Its early, northern section, with two lanes each way, has some odd junctions, most notably the very extravagant free-flowing interchange at Motherwell, while the newer, southern sections form a smooth, well-engineered modern road through spectacular scenery. Whatever your views on the many oddities and controversies of this motorway route, it would be hard to argue that it's ever dull.
River Clyde
Bothwell
