Useless Multiplexes

[McDanger]

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

The A91 also multiplexes with the M90 J7 and J8

[GrahamP]

For many years the A73 had a useless multiplex with the A702, with the A73 ending at its junction with the A74 at Abington, and the A702 continuing to St John's Town of Dalry (via another multiplex, with the A74). Presumably the idea was that a two-digit road should end at a junction with another two0digit road. Nowadays the A73 ends where it meets the A702.

[TS]

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!

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.

An excellent description in the top post and a clever reasoning in the first reply, which makes perfect sense and I'm pretty sure that was indeed the case.

The part between the railway station and County Gates was opened on 20 March 1973. However, the joining of the A35, through St. Paul's Road and St. Swithun's Road South – the short dual-carriageway sections by the back of Asda and continuing past the Abbey Life building to Christchurch Road – were not fully completed till about 10 years later. Up to that point, as Jimbo points out, the A35 would have continued along Christchurch Road and into town to County Gates.

Now the A35 joins the A338 at the railway station, the multiplex is indeed pointless since the A338 does not continue beyond the multiplex. The 'old' A35 through town is now essentially the southern town-centre by-pass (if it's possible for a town like Bournemouth to have a southern by-pass!) and this is now the B3066.

In the now defunct Waverley Road, now just a short stretch of tarmac used as a turning circle at the end of Cotlands Road, you can still see the faded arrows painted on the road surface, from the days when it was the westbound part of a one-way system (its eastbound counterpart being the first segment of Southcote Road and then of St. Swithun's Road), all surrounded by dense building, before the St. Swithun's Road South dual carriageway was put through. See this picture.

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.

The Spur Road, from the Cooper-Dean Roundabout (A3060 junction) [the flyover went in in 1987] and on to Richmond Park Road (A3049) came first, in the 60s. The section from Richmond Park to County Gates went through in the early 70s, with all those long , straight parallel residentail roads severed to accommodate it. The A338 at that time would have been Holdenhurst Road, which runs alongside most of the Wessex Way and used to come out at a humongous roundabout where the off-slip for King's Park football traffic now stands.

[GrahamP]

The A91 also multiplexes with the M90 J7 and J8

That's hardly a useless multiplex though, is it?

[Stevie D]

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

The A91 also multiplexes with the M90 J7 and J8

That isn't a useless multiplex because both roads continue at both ends of the shared section. A multiplex is only "useless" if one road starts/finishes at one end of the muitiplex (and therefore the shared road could be given the number of the other road and then there would be no multiplex and no gap in the other road number)

[multiraider2]

The A3071/B3306 multiplex is a useless one, as the A3071 gives up in St. Just and lets the B road take the route forward.

[agc2070]

I have always assumed that the A2008 in Hythe is a defunct road but if, as some maps and GPS systems show, it does still exist it would be a useless multiplex with the eastbound A259 because the entire 200 yard road also would be a multiplex.

[Sunil_of_Yoxley]

I've got one for you!

A102 Blackwall Tunnel turning into the A12 and then popping out of the dual carriageway as a non-primary at Hackney Wick. Better IMO to transfer the A12 number to the A11 west of Bow. Though that would mean of course that the A11 is stranded at Stump Cross - but hey you got the M11 to take you south!

[Richardf]

So could any of these be abolished without causing confusion or create yet another numbering anomaly?

I know that abolishing the A30/A303 one wouldn't make sense to most drivers but my original example in Bournemouth could be done away with easily i think.

Any others?

[sgill77]

There's a really useless one here:

http://maps.google.com/maps/ms?ie=UTF8& ... 78864&z=16

The B4043 isn't bracketed on the sign, so it's not just a "leading to" flag. The B4043 really starts about 200 yards along the A458. I assume they chose to sign it here because the A456 (which it leads to) can only be accessed directly from the roundabout in the opposite direction.

[Mark Hewitt]

Presumably a useless multiplex is where a road enters the multiplex but fails to emerge from it?

[nowster]

Presumably a useless multiplex is where a road enters the multiplex but fails to emerge from it?

It's where a dominant road multiplexes with another road, its number taking precedence. The dominant road number then ends and the other road continues on the other side of the multiplex.

For example, using hypothetical numbers:

Code: Select all

                               |
                               |
                            [G3232]
                               |
                               |
----[D123]-----+-----[D22]-----+-----[D123]----
               |
               |
             [D22]
               |
               |

[rick9525]

One near me is the following

At Jucntion 25 of the M60 the A560 mutiplexes with the A6017 towards Bredbury, no issues here. These 2 then form a 3rd Multiplex with the B6104 from Stockport at Morrisons(old A560 route).

The A6017 and B6104 then turn off shortly afterwards through Bredbury to the crossroads with the A627. The B6104 then carries on to Marple Bridge where as the A6017 stops there.

The only reason I can think of is a lot of lorries use the route to reach the A627 and the direct link from the A560 and A627 is further up and the A627 at this this point is very narrow, so they don't want lorries using it thus designate the link as an A road.

On a side note the short triple multiplex is a notorious bottleneck.

[Sean Nelson]

in North Wales, the A541 and the A5119 in Mold is only a short multiplex with two roundabouts.

[kieron]

in North Wales, the A541 and the A5119 in Mold is only a short multiplex with two roundabouts.

It is, but it's a better road to use for either than the B5433 through the town centre, even when the latter is open to traffic. I can't think off-hand of a sense in which this could be considered useless.

[si404]

A34 with A33 (at least northbound)
A33 with A35 between Millbrook and Redbridge roundabouts, Southampton
A33 with A272 between M3 j9 and j10 (especially, given that, Southbound the junction is signed Winchester A272) - given it multiplexes with the M3 from j10-14, it's rather useless - have to double-check signage.

I don't think it counts if the road is of a different class, ie a B road coming either side of an A road (or vice versa in the case of the A603), or things like the southern end of the M5, eastern end of the M62, etc.

Definite wiki page here!

[Jam35]

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.

And it could be argued that the M4 hides the A483 from Swansea West (J47) to Pont Abraham (J49).

[nowster]

And it could be argued that the M4 hides the A483 from Swansea West (J47) to Pont Abraham (J49).

Not forgetting that the M60 hides the M62 from Simister to Eccles.

I've encountered people lost on Regent Road (end of M602) who've come from Liverpool direction and wanted the M62. I've also known people follow the M60 round to J20, when they really wanted the A627(M) (M62 J20).

[stu531]

Do you think that could be resolved by signing the Eccles-Simister section as not M60 (M62), but 'M60/M62', if you like? On many of the signs, the M62 approaching Eccles from the west isn't signed so significantly. You can see why people see the M60 off-slip as a different motorway, which wasn't the case (as much) prior to the conversion to M60.

Situation might be helped if/when the construction of the new main line of M62 to Worsley shaves the corner off.

[Owain]

Re. other multiplexes involving motorways: I believe the M40 'carries' both the A34 and the A41 in a multiplex from Bicester to Birmingham. This multiplex is so long that I can hardly see the point of continuing the same road numbers at the other end.