M5 Junction 29 Works

The study of British and Irish roads - their construction, numbering, history, mapping, past and future official roads proposals and general roads musings.

There is a separate forum for Street Furniture (traffic lights, street lights, road signs etc).

Registered users get access to other forums including discussions about other forms of transport, driving, fantasy roads and wishlists, and roads quizzes.

Moderator: Site Management Team

User avatar
jackal
Member
Posts: 6075
Joined: Tue Jan 08, 2008 23:33
Location: M6

M5 Junction 29 Works

Post by jackal » Sat Jan 09, 2010 20:40

M5 J29 is nothing special at the moment - the traffic lights one encounters going from M5Nb to the A30Eb are in stark contrast to the quality of the rest of the A30 up to and past Honiton - but Devon County Council are determined to make things worse. Their 'improvements' include two extra sets of lights for M5Nb->A30Eb and signalization of the currently freeflow A30Wb->M5Sb movement.

I really can't understand why the mostly-sensible HA are buying into the 'improvement' fantasy - the only slight element of improvement is the addition of A30Eb->M5Sb which could have been added with far fewer of the new conflicts. The draft orders have been published but there is maybe still some hope that a public enquiry is needed and proves problematis, or that the credit crunch strikes.

User avatar
Truvelo
Member
Posts: 16346
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Truvelo » Sat Jan 09, 2010 21:08

This is a really poor proposal. If it was in the US it would no doubt contain far more freeflow. Give me a little time and I'll draw something far superior :wink:
How would you like your grade separations, Sir?
Big and complex.

SteveA30
Member
Posts: 5213
Joined: Fri May 06, 2005 12:52
Location: Dorset
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by SteveA30 » Sat Jan 09, 2010 21:15

Don't I bloody know it!
It is part of a huge development along the old A30 near Rockbeare. I had a phone conversation with someone from DCC last summer about it. He didn't think that through traffic would be held up, as I had pointed out.

I intend to write to the HA about this and, J25 at Taunton. Why aren't they insisting on keeping freeflow at J29 as part of the development, even with the new movements. The summer holiday queues will go back past the Airport probably. Using the old road won't work, as that will no doubt be filled with rbts and lights at every new junction in the new town. I may have to use the A3052 and, B3180 to avoid the whole area, although that will still mean multiple lights in the e/bnd direction at J30 :bang:

In the case of J25, why didn't they insist on the Henlade bypass and new M5 junction being built before construction of the Park'n' Ride ruins the current A358.
If they want to make the M5 inaccessable, just close off the junctions altogether.

User avatar
SouthWest Philip
Member
Posts: 3066
Joined: Sun Mar 31, 2002 19:35
Location: Evesham, Worcestershire

Re: Awful things happening to M5 J29 (A30)

Post by SouthWest Philip » Sat Jan 09, 2010 21:28

The stupid thing is that, given the proposed eastern bypass for Clyst Honiton linking the Exeter Airport junction with the old A30, there is no real need for the local junction east of M5 junction to be kept anyway. They sure as hell shouldn't be adding an at-grade junction to an otherwise fully grade-separated trunk road. Idiots!!

I wish I had the same computer skills, and software packages, as Truvelo! Then I'd be able to show you my plan for this junction... Basically something retaining/enhancing the free-flow between the M5(S)<>A30(E) whilst adding a full-access junction on the M5 just to the north, perhaps utilising an existing overbridge.

User avatar
Truvelo
Member
Posts: 16346
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Truvelo » Sun Jan 10, 2010 13:13

I've had a good look at these plans and firstly I don't like to see new development outside the bypass. The bypass for Exeter is the M5. The bypass forms an effective barrier against development but once breached it then becomes hemmed in by further development until it gets completely surrounded by business parks. This puts additional pressure on junctions. I can see the area where it says Blackhorse on the map becoming a suburb of Exeter very soon.

As others have side, the proposed Clyst Honiton Bypass means the planned traffic lights immediately east to the M5 aren't needed. Therefore M5 J29 could be made similar to this I drew a few years ago. The southbound exit slip is looped which removes the existing traffic lights so all A30-M5 South movements are freeflow. Exeter to M5 South still wouldn't be possible so a right turn lane could be added to the eastbound A30 under the M5. The looped slip road to the A30 East would join the A30 after the right turn lane meaning it would still be freeflow. A house near the southeast corner of the junction would need demolishing to make way for the A30 to M5 South slip.

Image
How would you like your grade separations, Sir?
Big and complex.

DavidBrown
Member
Posts: 8306
Joined: Sun May 29, 2005 00:35

Re: Awful things happening to M5 J29 (A30)

Post by DavidBrown » Sun Jan 10, 2010 14:03

I've known about these plans for a while now (I'm sure they have been discussed elsewhere?) It is worth pointing out that there are two seperate developments here. The J29 changes are to do with the new Exeter Science Park, whilst the Clyst Honiton bypass is part of the Cranbrook new town.

Truvelo - I like your ideas for J29, but J30 would cause horrendous weaving problems. Here's my (slightly more ambitious) plans;
M5Exeter.png
With two key junctions within half a mile of each other, I've added collector/distributor carriageways to the M5, and the A30 for a short distance. J29 really needs to be a full access junction, with the A30 dual carriageway, the airport, and the Met Office all of that one junction. I've kept long distance A30 - M5(S) traffic seperate with the freeflow slips, and kept the rest of the junction relatively simple with a 3 level stack.

For J30, I've removed the biggest problem - Exeter Services. The site is simply not suitable for a service area, and removing it will help J30 straight away. A freeflow slip to the M5 north from the A379 is all that's really needed here - improvements to the roundabouts below should suffice.

User avatar
Truvelo
Member
Posts: 16346
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Truvelo » Sun Jan 10, 2010 14:34

I must say your mapping skills are getting much better. I would never have dreamed of doing something that complex at J29. It's certainly better than the OS who forgot to colour the A379 red in between the railway bridge and the yellow road just to the left :wink:

As good as your plan is there's one thing I'm not too sure about. All trafic using J30 to and from the north has to use the roundabout at J29. I'm also unsure as to whether the long sweeping slip road from the M5 to the A30 east will fit as there's a factory in the way which is why I've left the southwest corner of J29 alone in my plan.
How would you like your grade separations, Sir?
Big and complex.

DavidBrown
Member
Posts: 8306
Joined: Sun May 29, 2005 00:35

Re: Awful things happening to M5 J29 (A30)

Post by DavidBrown » Sun Jan 10, 2010 14:51

Must admit I hadn't noticed the uncolured A379!

Three businesses would need relocating - a B&Q store and a Royal Mail depot, both of which would be fairly easy to relocate (especially with Exeter Services gone), and one smaller unit. As for the roundabout, adding a small slip from the C/D carriageway to the main carriageway wouldn't be too difficult, but my main concern was, again, weaving.

M5Lenzar
Former Member
Posts: 4477
Joined: Wed Apr 06, 2005 14:39

Re: Awful things happening to M5 J29 (A30)

Post by M5Lenzar » Sun Jan 10, 2010 16:52

J29 has always been a bodge, AIUI..the original design was full access but with cloverleaf types loops.

Can't they just rip the whole thing up and instead have an east facing fork onto the M5? Most traffic here would be M5S<->A30 anyway, with A30<->A3015 being a secondary concern.

User avatar
Chris5156
Member
Posts: 14405
Joined: Thu Sep 06, 2001 21:50
Location: Hampshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Chris5156 » Sun Jan 10, 2010 17:25

M5Lenzar wrote:J29 has always been a bodge, AIUI..the original design was full access but with cloverleaf types loops.
Not full access - it would have allowed traffic to and from the A30 east of Exeter to access the M5 in either direction. Traffic to and from the west could only go straight through onto the A30. There would have been two loops west of the M5 and two simple left-turns east of it.

User avatar
Truvelo
Member
Posts: 16346
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Truvelo » Sun Jan 10, 2010 19:41

Chris5156 wrote:Not full access - it would have allowed traffic to and from the A30 east of Exeter to access the M5 in either direction. Traffic to and from the west could only go straight through onto the A30. There would have been two loops west of the M5 and two simple left-turns east of it.
Are you sure it even offered these movements? I thought prior to the A30 dualling it allowed A30 to M5 South only?
How would you like your grade separations, Sir?
Big and complex.

M5Lenzar
Former Member
Posts: 4477
Joined: Wed Apr 06, 2005 14:39

Re: Awful things happening to M5 J29 (A30)

Post by M5Lenzar » Sun Jan 10, 2010 19:57

Truvelo wrote:
Chris5156 wrote:Not full access - it would have allowed traffic to and from the A30 east of Exeter to access the M5 in either direction. Traffic to and from the west could only go straight through onto the A30. There would have been two loops west of the M5 and two simple left-turns east of it.
Are you sure it even offered these movements? I thought prior to the A30 dualling it allowed A30 to M5 South only?
That's the cut down version that was built (and which I can remember took years to 'fix'). Chris and I were talking about the original plans.

User avatar
Truvelo
Member
Posts: 16346
Joined: Wed May 29, 2002 21:10
Location: Staffordshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Truvelo » Sun Jan 10, 2010 20:53

So if the original design was built it would have caused weaving on the northbound M5 :?
How would you like your grade separations, Sir?
Big and complex.

User avatar
Chris5156
Member
Posts: 14405
Joined: Thu Sep 06, 2001 21:50
Location: Hampshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Chris5156 » Sun Jan 10, 2010 21:14

Truvelo wrote:So if the original design was built it would have caused weaving on the northbound M5 :?
No, there was a C/D carriageway for that, and it was built - the northbound off-slip over the top of the A30 is built ready.

M5Lenzar
Former Member
Posts: 4477
Joined: Wed Apr 06, 2005 14:39

Re: Awful things happening to M5 J29 (A30)

Post by M5Lenzar » Sun Jan 10, 2010 22:47

Chris5156 wrote:
Truvelo wrote:So if the original design was built it would have caused weaving on the northbound M5 :?
No, there was a C/D carriageway for that, and it was built - the northbound off-slip over the top of the A30 is built ready.
Is that why the M5 is D4M between J29 and J30? The two junctions don't strike me as two that traffic would travel between.

Why was such a strange design chosen in the first place, anyway, surely two roundabouts would have been better?

User avatar
Chris5156
Member
Posts: 14405
Joined: Thu Sep 06, 2001 21:50
Location: Hampshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Chris5156 » Mon Jan 11, 2010 08:26

M5Lenzar wrote:
Chris5156 wrote:
Truvelo wrote:So if the original design was built it would have caused weaving on the northbound M5 :?
No, there was a C/D carriageway for that, and it was built - the northbound off-slip over the top of the A30 is built ready.
Is that why the M5 is D4M between J29 and J30? The two junctions don't strike me as two that traffic would travel between.
No, it's the over-long northbound off-slip. It exits the M5 very early and runs parallel, ready for the northbound on-slip to merge with it before the bridge over the A30.
Why was such a strange design chosen in the first place, anyway, surely two roundabouts would have been better?
Not sure I understand this bit - are you suggesting a dumbbell would have been a better way to connect two trunk routes than a free-flowing junction?

A307Patrick
Member
Posts: 90
Joined: Thu Nov 19, 2009 15:16

Re: Awful things happening to M5 J29 (A30)

Post by A307Patrick » Mon Jan 11, 2010 10:44

SteveA30 wrote:Don't I bloody know it!
It is part of a huge development along the old A30 near Rockbeare. I had a phone conversation with someone from DCC last summer about it. He didn't think that through traffic would be held up, as I had pointed out.

I intend to write to the HA about this and, J25 at Taunton. Why aren't they insisting on keeping freeflow at J29 as part of the development, even with the new movements. The summer holiday queues will go back past the Airport probably. Using the old road won't work, as that will no doubt be filled with rbts and lights at every new junction in the new town. I may have to use the A3052 and, B3180 to avoid the whole area, although that will still mean multiple lights in the e/bnd direction at J30 :bang:

In the case of J25, why didn't they insist on the Henlade bypass and new M5 junction being built before construction of the Park'n' Ride ruins the current A358.
If they want to make the M5 inaccessable, just close off the junctions altogether.
Not content with cancelling all outstanding dualling along the A303/A30 between the M3 and M5, the authorities now want to mess up the one scheme which did happen over the last 20 years or so :bang: . I'll write to the HA too.

(What is the latest with the Henlade bypass? Surely they should move ahead with this asap now that the full South Petherton to Taunton dualling and GSJ'ing has been shelved? I hope it will be D2 from the current short bit of DC on the A358 to M5 J25, with no roundabouts or traffic lights, or am I expecting too much?!)

User avatar
jackal
Member
Posts: 6075
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: Awful things happening to M5 J29 (A30)

Post by jackal » Mon Jan 11, 2010 12:26

Chris5156 wrote:
Truvelo wrote:So if the original design was built it would have caused weaving on the northbound M5 :?
No, there was a C/D carriageway for that, and it was built - the northbound off-slip over the top of the A30 is built ready.
Fascinating. Are any of the other abnormally long slips around the country explicable in this way?

Of course, as Girton can testify, C/D carriageways of this sort don't eliminate weaving, they just take it off the mainline.
Chris5156 wrote:
M5Lenzar wrote:Is that why the M5 is D4M between J29 and J30? The two junctions don't strike me as two that traffic would travel between.
No, it's the over-long northbound off-slip. It exits the M5 very early and runs parallel, ready for the northbound on-slip to merge with it before the bridge over the A30.
I assumed the D4M was just to handle weaving from the proximity of merges/demerges. If the concern was specifically with one slip why do both carriageways get the extra lane?
Why was such a strange design chosen in the first place, anyway, surely two roundabouts would have been better?
Not sure I understand this bit - are you suggesting a dumbbell would have been a better way to connect two trunk routes than a free-flowing junction?
Quite - I wish we had more partial access freeflow junctions where primary routes and motorways meet (M5 J10 is one that actually got built).

User avatar
Chris5156
Member
Posts: 14405
Joined: Thu Sep 06, 2001 21:50
Location: Hampshire
Contact:

Re: Awful things happening to M5 J29 (A30)

Post by Chris5156 » Mon Jan 11, 2010 12:42

jackal wrote:
Chris5156 wrote:
Truvelo wrote:So if the original design was built it would have caused weaving on the northbound M5 :?
No, there was a C/D carriageway for that, and it was built - the northbound off-slip over the top of the A30 is built ready.
Fascinating. Are any of the other abnormally long slips around the country explicable in this way?
There's the ones around Hedge End on the M27 that were supposed to accommodate an unbuilt service area. One is in use as the off-slip, one is sitting there next to the motorway but was never put into service.

Not sure about any others.
I wish we had more partial access freeflow junctions where primary routes and motorways meet (M5 J10 is one that actually got built).
That's not even a primary route, IIRC - and neither is the M27/A32 junction, which is very similar.

User avatar
A303Chris
Elected Committee Member
Posts: 3081
Joined: Mon Sep 20, 2004 14:01
Location: Reading

Re: Awful things happening to M5 J29 (A30)

Post by A303Chris » Mon Jan 11, 2010 13:36

That is a disaster, but the free flow link between A30 W/B and M5 S/B could still be inplace as the location of the signals is not shown. The slip from the A30 could free flow into lane 1 of the slip and the lane 2 of the slip could be for traffic going through the junctions from the A30 E/B and new access road. Not ideal but it would work.

I would like to see the Stage 1 and Stage 2 Safety Audit on it. May be a freedom of information request
The M25 - The road to nowhere

Post Reply