Useless Multiplexes

[Richardf]

The term 'Multiplex' is oft used on Sabre and i think the definition is quite clear - Two or more route numbers sharing the same stretch of road space. What is less clear is the lesser used term of 'Useless Multiplex'. I have often wondered what makes a multiplex 'useless'!

The most well used example of a useless multiplex is the A30/A303 one in Hampshire, so I am guessing that the phrase means a multiplex where on of the roads/routes starts at one end of the multiplex and that for useless you could also read 'unnessesary' since the start/end of the multiplexing route could be elsewhere along the other route and avoid a multiplex entirely!

Would this be a correct definition or does the term have other meanings in a roads context?

What other well known 'useless multiplexes' are there. I discovered one last night in Bournemouth with the A35 and A338. The A338 and A35 multiplex along the 'Wessex Way' (town centre bypass). The A338 starts on the A35 at the County Gates gyratory, and leaves the A35 at the eastern end f the bypass near the railway station. The A338 then heads to Ringwood, the A35 to Christchurch.

I had always assumed the Wessex Way bypass was the A35 (replacing the A35 that ran through the town centre originally) and the A338 took over after the station as 'The Bournemouth Spur Road'. According to the signage the A338 follows the whole route, resulting in a completely pointless multiplex with the A35. That said I suppose like the A30/A303 one it has been done this way for route continuity and it is only people like us who notice these anomalies!

[Jimbo]

The reason for the A35/A338 multiplex is historical. When the A338 Wessex way was built, the old route through Bournemouth was still the A35. I would need to check my old maps to see when the A35 designation was lost, but they were both there for a while. The current junction between the A338 Wessex Way and the A35 next to the railway station was also a later addition than the rest of the road, so the change may have happened then.

There were also plans to extend the A338 Wessex Way westwards through Parkstone to connect to the A3049, and then later another plan for it to turn north and connect with the planned A3049 Wallisdown bypass. I suspect in both cases the road would have been numbered the A338.

So we have a useless multiplex because no-one has gone back and renumbered the road from before it was a useless multiplex.

Jim.

[Johnathan404]

There's quite a mess of multiplexes at M3 J9. The A272 mutliplexes with the A31, the A34 and Spitfire Link. On top of that, the A33 and A34 multiplex to reach J9 - for the past 70 years this has been the A33, but I think the A34 has now become the dominant route. Meanwhile, the Spitfire Link could be either the end of the A34/A33, a spur of the A31 or part of the A272, depending on which sign you read. And does the A33 multiplex with the M3?

A right mess - but there must be some useless multiplexes in there.

[Stevie D]

One of the most recent examples is the road from Bedford to Black Cat, which is a multiplex of A421 and A428. But, guess what, it's signed as A421, which ends at Black Cat, so there is effectively a gap in the A428. The new road could have been numbered A428 as the old road was, and then everyone would have been happy!

[NICK 647063]

One of the most recent examples is the road from Bedford to Black Cat, which is a multiplex of A421 and A428. But, guess what, it's signed as A421, which ends at Black Cat, so there is effectively a gap in the A428. The new road could have been numbered A428 as the old road was, and then everyone would have been happy!

That section of the A428 through great barford was renumbered to the A421 many years ago when the bedford southern bypass was built, as the main route was the A421 from MK towards cambridge, they should have just renumbered the rest of the A428 to cambridge as the A421 !!

[skiddaw05]

There's a bit of an odd situation at Natnwich with the A500 and the A51. The signing of the bypass between the 500 and the A530 doesn't seem to make up its mind as to whether this is the A500 or the A51, though it would appear that the A51 goes through the middle of the town. However the short section of primary road between the roundabout at the start of the bypass and where the A51 comes up from the south also looks like it's the A51 as well, which would make this last section of the A500 to the A530 a U.M.

[Jimbo]

Not sure if this on the A3029/A370 in Bristol is a useless Multiplex or a mapping mistake.

The A370 mutliplexes with the A3029 through Ashton Gate, but on the OS 1:25000 maps, the first part of the A370 is then shown as the A3029 up until the junction with B3120. As the A3029 also continues into Cumberland Basin, this looks more like a mapping mistake.

Jim.

[ForestChav]

There's a bit of an odd situation at Natnwich with the A500 and the A51. The signing of the bypass between the 500 and the A530 doesn't seem to make up its mind as to whether this is the A500 or the A51, though it would appear that the A51 goes through the middle of the town. However the short section of primary road between the roundabout at the start of the bypass and where the A51 comes up from the south also looks like it's the A51 as well, which would make this last section of the A500 to the A530 a U.M.

They recently fixed that - all of the bypass is the A51 now.

[Sean Nelson]

In Abergele in North Wales, the A547 and A548 multiplex for a short time.

[Richardf]

The reason for the A35/A338 multiplex is historical. When the A338 Wessex way was built, the old route through Bournemouth was still the A35. I would need to check my old maps to see when the A35 designation was lost, but they were both there for a while. The current junction between the A338 Wessex Way and the A35 next to the railway station was also a later addition than the rest of the road, so the change may have happened then.

There were also plans to extend the A338 Wessex Way westwards through Parkstone to connect to the A3049, and then later another plan for it to turn north and connect with the planned A3049 Wallisdown bypass. I suspect in both cases the road would have been numbered the A338.

So we have a useless multiplex because no-one has gone back and renumbered the road from before it was a useless multiplex.

Jim.

I suppose it partly depends on which sections of the current A338 were built first, the Town bypass (wessex way) or the link to the A31 at ringwood ('the spur road' as locals call it). If the sur road came first as the A338 then it is logical that the subsequent town bypass would also be the A338. If however the town bybass section was first (and I have a feeling it might have been) then this would have been a replacement for the A35 through the town and thus should be (or wouls have been to start with at least) the A35. Like i said in the above post I can see the logic of extending the A338 all the way along, particularly if it was intended to go further. As it stands it still creates a useless multiplex, practical or not.

[t1(M)]

The A205 is the dominant member of a short multiplex with the A315, between Kew Bridge and the Chiswick roundabout, despite the fact that only the A315 emerges at the other end to go towards Hammersmith. the reason, presumably, is so that the A205 SCR and A406 NCR actually meet up.

[Jeni]

In Abergele in North Wales, the A547 and A548 multiplex for a short time.

Do you read threads before you reply?

[M5Lenzar]

The M5 ends at J31, whilst multiplexing with the A30 and A38.

Is this the only one involving a motorway?

[dvboy]

A158 and A15, Lincoln Bypass, here.

I think we've has this topic before.

[Richardf]

The M5 ends at J31, whilst multiplexing with the A30 and A38.

Is this the only one involving a motorway?

Cant see how thats a useless multiplex? If a motorway starts and ends at certain point it starts or ends at a certain point, you cant say that for the length it multiplexes with an A road that road should have priority if it continues either side of the multiplex.

Nor can you say that the A30 or A38 make it 'useless' since the both continue either side of the multiplex, albeit after a big gap in the A38's case!

[Stevie D]

The M5 ends at J31, whilst multiplexing with the A30 and A38.

Is this the only one involving a motorway?

Nope.

M62 from J37 to J38 hides the A63
M54 from J5 to J7 hides the A5
M45 from J* to J* hides the A45

and the entire lengths of the M69 and M90 form multiplexes with the A46 and A90 respectively.

[Halstead]

A158 and A15, Lincoln Bypass, here.

I think we've has this topic before.

Irritatingly we have had them before, as well as the couple involving central reservations.

http://www.sabre-roads.org.uk/forum/vie ... ultiplexes

[skiddaw05]

Certain topics are bound to reappear from time to time, especially ones like these with an all round intrest to the Sabristri. I can't see that it's anything to be irritated about.

[Jimbo]

The reason for the A35/A338 multiplex is historical. When the A338 Wessex way was built, the old route through Bournemouth was still the A35. I would need to check my old maps to see when the A35 designation was lost, but they were both there for a while. The current junction between the A338 Wessex Way and the A35 next to the railway station was also a later addition than the rest of the road, so the change may have happened then.

There were also plans to extend the A338 Wessex Way westwards through Parkstone to connect to the A3049, and then later another plan for it to turn north and connect with the planned A3049 Wallisdown bypass. I suspect in both cases the road would have been numbered the A338.

So we have a useless multiplex because no-one has gone back and renumbered the road from before it was a useless multiplex.

Jim.

I suppose it partly depends on which sections of the current A338 were built first, the Town bypass (wessex way) or the link to the A31 at ringwood ('the spur road' as locals call it). If the sur road came first as the A338 then it is logical that the subsequent town bypass would also be the A338. If however the town bybass section was first (and I have a feeling it might have been) then this would have been a replacement for the A35 through the town and thus should be (or wouls have been to start with at least) the A35. Like i said in the above post I can see the logic of extending the A338 all the way along, particularly if it was intended to go further. As it stands it still creates a useless multiplex, practical or not.

Just checked my maps of the area and it falls between editions !! It looks like the Spur road was built before most of the Wessex way - I one map showing the spur road as far as Queens park, and a small section in the centre of the Wessex way as built. This shows 2 A roads through Bournemouth, the old A35 still as A road, along with the small bit of Wessex way and various bits of residential street to join it up. Unfortunately, there are no road numbers, so it is unclear how it was numbered.

Nevertheless, I agree it is a useless multiplex.

Jim.

[haymansafc]

They recently fixed that - all of the bypass is the A51 now.

I can also confirm that this is now the case. However, this must have happened only recently. I'm down that way fairly regularly (around once a month, sometimes every few weeks) and it was still the A500 the last time I used it, although the new lattice posts for the replacement signs were going up.

This renumbering has been on the cards for some time though, at least the last few years to my knowledge. I don't know why it wasn't made the A51 when it was first built, as back then the A500, before the Shavington Bypass, met the A51 here, when this used to be a junction until early on this decade.

The old A51 though Nantwich is now unclassified from what you can tell on the ground. All old A51 signs have been removed although some of the posts remain with no signs attached to them. A couple of new white signs have gone up signing 'Nantwich Town Centre' and have no numbering on them.

Speaking of old posts, there is still one route confirmation sign on the renumbered A51 which still states it as the 'A500'.