M3 Junction 9 Improvements

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wrinkly
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Re: M3 Junction 9 Improvements

Post by wrinkly »

I haven't read all the docs yet, but I don't see why you can't build a new bridge to carry a new northbound A34 over the northbound A33, adjacent to the existing bridge carrying the southbound A34 over the northbound A33, thus converting the A34/A33 junction to a standard fork.

The new bridge would be at a quite high skew, and you'd also need a bridge over the Itchen, but at least all the weaving would then be on the left.

In other words what jackal said.
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Re: M3 Junction 9 Improvements

Post by Richardf »

910f4f31-7a25-4e77-b207-a03e32679939.png
Done a rough sketch of my version of the scheme. Current NB A34 becomes an LAR linking the A33 to the M3 junction and providing a non motorway route to A34.
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Re: M3 Junction 9 Improvements

Post by Herned »

Further to Richard A35's suggestion earlier, could the A33 northbound be reconfigured as below:

Image

The A33 could leave the northbound slip to the M3 between the two A34 carriageways. There appears to be a gap around 100m wide between them at that point. Then run a single lane all the way to join the existing A33 without touching the A34 mainline. It would need no extra bridges except over the Itchen. The diverge may need to be sharper than standards but it's surely safer than an offside exit, especially one that is mainly local so I would expect a large proportion of the traffic using it to be coming from Winchester and hence needing to weave across the A34
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Johnathan404
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Re: M3 Junction 9 Improvements

Post by Johnathan404 »

It's a shame the northbound crossing of the Itchen is not wide enough for a third lane, unlike the older(?) southbound bridge. Otherwise you could have had the design above but with the two roads merging to form a three-lane weaving section.

On another note, I realise the video isn't supposed to show the finer details, but its use of road signs is odd. The 2+2 A34/M3 sign at the start is a copy of the existing sign (the old-fashioned use of 'The Midlands' gives it away), but modified to suit the new layout. There are no other northbound signs. Southbound some new signs have been drawn, with incorrect fonts and posted in incorrect places, but at least showing the motorway regulations in the correct place. Still, I hope the background music is a feature of the new junction too!
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jackal
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Re: M3 Junction 9 Improvements

Post by jackal »

Herned wrote:Further to Richard A35's suggestion earlier, could the A33 northbound be reconfigured as below:

Image

The A33 could leave the northbound slip to the M3 between the two A34 carriageways. There appears to be a gap around 100m wide between them at that point. Then run a single lane all the way to join the existing A33 without touching the A34 mainline. It would need no extra bridges except over the Itchen. The diverge may need to be sharper than standards but it's surely safer than an offside exit, especially one that is mainly local so I would expect a large proportion of the traffic using it to be coming from Winchester and hence needing to weave across the A34
This is a nice innovative solution that saves a bridge compared to the more common suggestion of an additional A34 carriageway (option 11). But I don't know if it would be cheaper as your A33 carriageway is very close to both A34 carriageways and at a different elevation, necessitating extra structural content. You can see what I mean if you look at the narrow and increasingly steep central reservation at 3.40:

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Re: M3 Junction 9 Improvements

Post by Arcuarius »

It might help if the northbound M3 to A34 movement was two lanes throughout. Half the problem with J9 stems from the "use both lanes" signs, when any attempt to use lane 2 means a last minute dive across to lane 1 as the carriageway splits.
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Re: M3 Junction 9 Improvements

Post by 6637 »

jackal wrote:Consultation on the proposed option is now open. Maybe they could've done something about the weaving up to the A33 junction but it's basically good :)

Brochure: https://highwaysengland.citizenspace.co ... 0FINAL.PDF
Consultation page: https://highwaysengland.citizenspace.co ... rovements/
That section of weaving could be ameliorated (though not completely removed) by simply swapping the locations of the proposed Highways England access road and the J9 northbound onslips.

This wouldn't remove the weaving, of course, but it would increase the length of road in which the weaving occurs.
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Re: M3 Junction 9 Improvements

Post by Johnathan404 »

This morning the A34 southbound is closed due to a HGV overturning at the chicane.
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Re: M3 Junction 9 Improvements

Post by Herned »

jackal wrote:.... But I don't know if it would be cheaper as your A33 carriageway is very close to both A34 carriageways and at a different elevation, necessitating extra structural content...
Obviously there would be some cost involved but it would a) only need to be one lane wide; b) eliminates weaving completely and c) there will be lots of conveniently located earth-moving machinery and quite a lot of the area involved is going to be altered by the planned works anyway!
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Re: M3 Junction 9 Improvements

Post by mikehindsonevans »

Having watched the HE video flythrough, I have to say that I am impressed. Plus, not a traffic light in sight on the mainline traffic alignments.
Obviously, consultation will bring out detailed suggestions to enhance certain details, but overall this gets my vote. Roll on 2022.
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Re: M3 Junction 9 Improvements

Post by dcrc2 »

It seems you could lengthen the weaving distance considerably by looping the A34 onslip around under the dumbbell. I guess it would never happen though - building new slip roads through a National Park is fine, but Tesco's car park is sacrosanct.
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Re: M3 Junction 9 Improvements

Post by J6onM27 »

Looks good except for the weaving Winchester traffic heading northbound onto A33!

The only other issue will be M3 southbound is going to receive traffic at a faster rate off the A34. The M3 to M27 will need to at least 4 lanes to cover this, as it already stands it already chaos in rush hour without this increased flow. If I read somewhere this is due to "smart" treatment including most of M27.
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Re: M3 Junction 9 Improvements

Post by vlad »

J6onM27 wrote:Looks good except for the weaving Winchester traffic heading northbound onto A33!
From the video I can't see that it's going to be easy to reach the A33 from the A272 - it looks as though after joining the A34 you'd have to move over into the right-hand lane immediately. I can see other local roads becoming busier as traffic avoids the junction.
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Re: M3 Junction 9 Improvements

Post by RichardA35 »

Coming from A33 S/B towards Spitfire Link is a bit of a short weave approaching the roundabout - so tight the model made a van cut across from lane 2 on the roundabout...
miscreant car.jpg
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Re: M3 Junction 9 Improvements

Post by Stevie D »

RichardA35 wrote:Coming from A33 S/B towards Spitfire Link is a bit of a short weave approaching the roundabout - so tight the model made a van cut across from lane 2 on the roundabout...
I think it's great that they are trying to accurately model bad driving from vans!
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Re: M3 Junction 9 Improvements

Post by M19 »

RichardA35 wrote:Coming from A33 S/B towards Spitfire Link is a bit of a short weave approaching the roundabout - so tight the model made a van cut across from lane 2 on the roundabout...miscreant car.jpg
The entry and exit angles are awful too, so those using it can look forward to plenty of near misses, or worse still being sideswiped through entry path overlaps.
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Re: M3 Junction 9 Improvements

Post by darkcape »

Correct me if I'm wrong but didn't the A34/A33 originally open as 2 through lanes with a right-hand exit before being remarked in the mid 2000's - I'm assuming because they didn't like RH exits - so I wonder why it is being reinstated.

Otherwise I think this junction upgrade is a fairly good design, most importantly the A34 is freeflow.
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wrinkly
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Re: M3 Junction 9 Improvements

Post by wrinkly »

darkcape wrote:Correct me if I'm wrong but didn't the A34/A33 originally open as 2 through lanes with a right-hand exit before being remarked in the mid 2000's
Discussed on page 1 of this thread. Vierwielen and I both seemed to remember it was similar to today but with less paint.

Remember that when the junction first opened the M3 didn't exist, and the A33 was at least as important a route as the A34.

Or are you talking about after the M3?
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Re: M3 Junction 9 Improvements

Post by Bryn666 »

An offside exit is hardly impossible to deal with is it...

We don't have carnage in Newcastle or Leeds where offside exits are in use daily.
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Re: M3 Junction 9 Improvements

Post by RichardA35 »

Bryn666 wrote:An offside exit is hardly impossible to deal with is it...

We don't have carnage in Newcastle or Leeds where offside exits are in use daily.
Combined with vehicles accelerating on a downhill gradient on the M3 to A34 link (> 2.39 on video) it makes the weave interesting to say the least.
I counted 24 white lines in the weave from the start of the merge to the start of the diverge ~220m
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