Why does the M6 turn into the M74 in Scotland?

[mccririck]

I've always wondered why it couldn't just be the M6 all the way?

[Steven]

I've always wondered why it couldn't just be the M6 all the way?

Actually, it doesn't turn into the M74, but the A74(M).

M74 and A74(M) History gives a good overview.

[Chris Bertram]

It must be said that as M74 and A74(M) have a continuous junction numbering sequence, the distinction between the two roads is now entirely arbitrary, but until the Scottish transport authority sees fit to fix it, it will remain. The concept of M6 running through to Glasgow was to all intents and purposes dead as soon as Scottish devolution happened, whichever party was in charge in Hollywood. A few signs close to the border whose "temporary" plates have dropped off remain to remind us of the original plan, that's all.

[BOH]

......the concept of M6 running through to Glasgow was to all intents and purposes dead as soon as Scottish devolution happened, whichever party was in charge in Hollywood.

In Hollywood??

[Chris Bertram]

......the concept of M6 running through to Glasgow was to all intents and purposes dead as soon as Scottish devolution happened, whichever party was in charge in Hollywood.

In Hollywood??

S*dding autocorrect. Holyrood.

[Ronnie]

It must be said that as M74 and A74(M) have a continuous junction numbering sequence, the distinction between the two roads is now entirely arbitrary, but until the Scottish transport authority sees fit to fix it, it will remain. The concept of M6 running through to Glasgow was to all intents and purposes dead as soon as Scottish devolution happened, whichever party was in charge in Hollywood. A few signs close to the border whose "temporary" plates have dropped off remain to remind us of the original plan, that's all.

The DVSA check point at Beattock Summit has an unplated sign saying M6 South - https://goo.gl/maps/o7AjaUvVpED21Dnx8

[Duncan macknight]

It’s a rather long and complex tale so here’s a brief overview. The A74 Glasgow Carlisle road was upgraded to a dual carriageway in the 1950s and 1960s. This was completed in May 1973 with Gretna Bypass opening. The M6 from England simply connected into it (mid 1960s).

Through the 1970s there was calls for the Glasgow section of M74 to be extended all the way to the M6 at Carlisle. An extension did occur in 1986/87 taking the M74 to J12. In 1987 the decision was taken to overhaul the A74 dual carriageway to full Motorway, mostly due to its age and increasing traffic flows. This was built rather quickly from J12 to Gretna Green where it stopped short of M6 J44 by several miles (See Cumberland Gap for more).

The issue of Numbering goes back to the 1920s/1930s road renumbering where England was Given Numbers 1-6 and Scotland Given 7-9.
The M6 was a Bypass of the A6 Trunk road so it was called M6.
The Glasgow M74 was a Bypass Of the A74 so it was called M74. The A74(M) issue was basically a temporary Number while the Motorway was being built in the 1990s. It was interned the M6 WOULD extend all the way to J14, where the M74 goes to Glasgow and A702 Meanders it’s way towards Edinburgh. This was intended to be bypassed by a Motorway (M702??) but these plans were shelved in the late 1990s.

Why it’s not been extended or changed since then is that there is very little interest in changing route numbers and theses plans of the M6 Scotland extension have been dropped and never picked up again....

[mikehindsonevans]

Autocorrect strikes again? Who was interned?

[fras]

It’s a rather long and complex tale so here’s a brief overview. The A74 Glasgow Carlisle road was upgraded to a dual carriageway in the 1950s and 1960s. This was completed in May 1973 with Gretna Bypass opening. The M6 from England simply connected into it (mid 1960s).

Through the 1970s there was calls for the Glasgow section of M74 to be extended all the way to the M6 at Carlisle. An extension did occur in 1986/87 taking the M74 to J12. In 1987 the decision was taken to overhaul the A74 dual carriageway to full Motorway, mostly due to its age and increasing traffic flows. This was built rather quickly from J12 to Gretna Green where it stopped short of M6 J44 by several miles (See Cumberland Gap for more).

The issue of Numbering goes back to the 1920s/1930s road renumbering where England was Given Numbers 1-6 and Scotland Given 7-9.
The M6 was a Bypass of the A6 Trunk road so it was called M6.
The Glasgow M74 was a Bypass Of the A74 so it was called M74. The A74(M) issue was basically a temporary Number while the Motorway was being built in the 1990s. It was interned the M6 WOULD extend all the way to J14, where the M74 goes to Glasgow and A702 Meanders it’s way towards Edinburgh. This was intended to be bypassed by a Motorway (M702??) but these plans were shelved in the late 1990s.

Why it’s not been extended or changed since then is that there is very little interest in changing route numbers and theses plans of the M6 Scotland extension have been dropped and never picked up again....

Actually, the M6 stopped north of Carlisle and there was the ghastly A74 dual-carriageway connecting M6 and M74. This is called the "Cumberland Gap" in the Wiki entry for the M6, and wasn't replaced until 2008

I suppose the Scottish government are looking for a site for a border post now. (only joking) !

[Steven]

The M6 was a Bypass of the A6 Trunk road so it was called M6.

This isn't the case at all. Motorway numbering in England and Wales doesn't work this way - it's only true (mostly) in Scotland.

[trickstat]

The M6 was a Bypass of the A6 Trunk road so it was called M6.

This isn't the case at all. Motorway numbering in England and Wales doesn't work this way - it's only true (mostly) in Scotland.

It's not until a little north of Wigan that they even come within 10 miles of each other.

[WHBM]

I suppose the basic question is, why when all-purpose roads were initially numbered (1920 ?) did the A1 get numbered right over the border and all the way to Edinburgh, but the A6 did not get comparably numbered through to Glasgow.

The M6 was a Bypass of the A6 Trunk road so it was called M6.

This isn't the case at all. Motorway numbering in England and Wales doesn't work this way

Actually it did in the original scheme. The M6 was "[London] to Carlisle". The M1 was "London to Yorkshire". These were the initial MoT expressions of the early 1950s. The M5/M50 were the first ones to break this mould, numbered a bit later.

[Steven]

I suppose the basic question is, why when all-purpose roads were initially numbered (1920 ?) did the A1 get numbered right over the border and all the way to Edinburgh, but the A6 did not get comparably numbered through to Glasgow.

1922.

Because the A1 was considered the most important route, and routing A6 to Glasgow would have broken the eventually chosen zonal systems, the A2 notwithstanding. It could have been however routed to Edinburgh without breaking things, but then how would the 7 zone have worked? Would you have then extended the 5 zone to meet the A8? It simply doesn't work.

The M6 was a Bypass of the A6 Trunk road so it was called M6.

This isn't the case at all. Motorway numbering in England and Wales doesn't work this way

Actually it did in the original scheme. The M6 was "[London] to Carlisle". The M1 was "London to Yorkshire". These were the initial MoT expressions of the early 1950s. The M5/M50 were the first ones to break this mould, numbered a bit later.

Actually, it didn't. Motorway numbers were not allocated in the early 1950s.

And besides, the early 1950s proposal for a motorway up the west coast of England was described as "Birmingham to Lancaster", not "London to Carlisle". There were absolutely no plans to build the motorway as far as Penrith at that time, let alone Carlisle. In addition, during the time period mentioned, the Midlands Link from Birmingham to Rugby was treated as a different motorway entirely from that heading north from Birmingham.

The M6 number was first suggested as a number for the Birmingham to Lancaster Motorway in April 1958. Prior to that it was "Motor Road 2", "MR.2" or "M.2" for short.

The Preston Bypass was labelled as "M6" solely because Lancashire County Council couldn't get an answer out of the Ministry so just unilaterally numbered it so.

National Archives files MT39/771 and MT112/67 are relevant here and valuable for anyone interested in the topic of motorway planning and proposals between roughly 1945 and 1970.

[gepree68]

I don't understand why the temporary number A74(M) (for the permanent number M6) was even considered at all for the motorway north of M6 J45.

Surely a temporary number should only be used when none of the route yet exists as the M* number. Of course M6 existed from M1 J19 all the way up to M6 J45.

[Steven]

Surely a temporary number should only be used when none of the route yet exists as the M* number. Of course M6 existed from M1 J19 all the way up to M6 J45.

Not when it's in isolated sections, and remember that the Cumberland Gap was a thing at the time - the M6 only extended to J44.

Where, however, a motorway is merely a by-pass along an existing route such as the Doncaster Bypass along Route A.1, it will not be given a separate M number, but in order to make it clear that it is a motorway and that motorway Regulations apply to it, the letter M will be added in brackets to the existing route-number - e.g. A.1(M) for the Doncaster Bypass. This will preserve the continuity of the route-number of long-distance all-purpose roads. Generally speaking by-passes that are eventually linked to form a continuous motorway will preserve the existing route-number (plus M in brackets) until they are so linked.

The A74(M) was constructed in a bunch of small sections, the idea of preserving the long-distance route number (so, A74 in this case) for these short sections until they were all joined up and then to apply the final number. Remember that during the construction period of A74(M) on a drive between Carlisle and the southern end of the M74 you would literally jump on and off the motorway sections constantly at a bunch of temporary terminii that were seemingly always changing.

I didn't say it was a good idea in this case, just that it fits exactly the original methodology that fell into general disuse in the mid-1970s. See the A48(M) Morriston Bypass and the A8(M) Renfrew Bypass (although both opened with the full motorway number) for other examples of this type where both M4 and M8 existed elsewhere at the time.

[Gareth]

Is the simple answer not that they simply started off as two separate motorways and there was never any guarantee that they'd ever meet?

The M74/A74 came from the central belt and headed south, so got a 7x number. M6 came off the M1 (and by extension London) and headed north.

1-6 number roads radiate from London whereas 7-9 radiate from Edinburgh. Despite this, it's always been a Great Britain system, with the separate numbers out of Edinburgh being more about the shape of the island rather than a distinct thing for Scotland. 7 number roads go into England, 6 number roads go into Scotland, as does, of course, the A1. The M6 ends just short of the border with Scotland, with the A74(M) taking over. You can see an A74(M) driver location sign just before the border. Only England has such things currently.

[Steven]

1-6 number roads radiate from London whereas 7-9 radiate from Edinburgh. Despite this, it's always been a Great Britain system, with the separate numbers out of Edinburgh being more about the shape of the island rather than a distinct thing for Scotland. 7 number roads go into England, 6 number roads go into Scotland, as does, of course, the A1. The M6 ends just short of the border with Scotland, with the A74(M) taking over. You can see an A74(M) driver location sign just before the border. Only England has such things currently.

Unfortunately you're conflating two (well, three actually...) entirely different systems.

All-purpose roads have one numbering system, motorways in England and Wales have a second, and motorways in Scotland have a third.

[Gareth]

But for the purposes we're talking about, the outcome is largely the same.

[Steven]

But for the purposes we're talking about, the outcome is largely the same.

Not really. They did start out as two entirely separate motorways without any plans to connect absolutely right there, but the quoted paragraph is actively incorrect for motorways, unfortunately.

The M5, for example, abolutely does not radiate from London but is correctly numbered within the numbering system used for motorways.

[Gareth]

I'm aware you're technically correct here but, again, within the context of what we're talking about, it's getting into "Big Ben's the bell, not the clock tower" territory.

The M6 meets the A74(M). One came from the north, one came from the south. The numbering scheme was therefore different. That's ultimately the point I was trying to make and you seem to concur with it.

Yes, M roads in England & Wales have a different scheme to A & B roads and the zoning isn't exactly the same but the pattern is similar in a broad sense, the M5 being the outlier for single digit motorways. For the purposes of what we're talking about, the M6 radiates from London, klick-wise with the numbers increasing northwards. The A74 and M74 radiate from the central belt and the klicks and junction numbers increment southwards, so neither were ever going to get a 6x number, whether M or A.

If I gave the impression it was all one numbering convention, then I apologise. I'm not one for purposely misleading.