A358 Taunton to Southfields

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

Post Reply
User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Fri Jan 05, 2018 22:28

DavidBrown wrote:Just a minor point that Homebase has closed down and it's now The Range. :)

Improving access for the A358 into Taunton is utterly pointless - all the traffic with just crash to a halt at Creech Castle even quicker and it may even end up making J25 worse. Getting traffic out of Taunton quicker may have some merit - something like this at Newport could work well.
I agree there are other constraints along Toneway, but how could removing traffic from J25 possibly make J25 'worse'? By freeing capacity on the roundabout you're (as you say) improving conditions for the outbound movements, as well as the movements that don't involve Toneway at all (especially A358<>M5).

Perhaps a one-way outbound flyover, a bit like this, would be worthwhile. I think they looked at a hamburger as a possibility for J25 but it's not cost effective as you'd have to tunnel under the motorway at great expense and the benefits of such a design are inherently modest. Speaking of which...
boliston wrote:There are plans to update creech castle junction with a "throughabout"

Page 41 (final page) of this pdf shows the new layout which looks a lot more efficient than the rather dated layout they now have http://heartofswlep.co.uk/wp-content/up ... ersion.pdf
I'm sceptical about whether that's really an improvement at all. The hamburger slightly improves throughput along the Toneway but this seems to be at the cost of the other movements gaining phases. Removing the four left turn filters seems an especially egregious example of signal-centric thinking.

boliston
Member
Posts: 141
Joined: Wed Dec 10, 2014 19:43
Location: Taunton
Contact:

Re: A358 Taunton to Southfields

Post by boliston » Fri Jan 05, 2018 23:51

jackal wrote: I'm sceptical about whether that's really an improvement at all. The hamburger slightly improves throughput along the Toneway but this seems to be at the cost of the other movements gaining phases. Removing the four left turn filters seems an especially egregious example of signal-centric thinking.
There are toucan crossing phases on the new layout which might add a small time to people doing a left filter turn but the current pedestrian route from the creech castle hotel to the other side of the A358 involves a huge detour as well as climbing over a footbridge - probably more extra time than the few extra seconds if left filtering traffic has to wait on a red phase.

Herned
Member
Posts: 801
Joined: Thu Jul 20, 2017 09:15

Re: A358 Taunton to Southfields

Post by Herned » Sat Jan 06, 2018 00:14

jackal wrote:I'm sceptical about whether that's really an improvement at all. The hamburger slightly improves throughput along the Toneway but this seems to be at the cost of the other movements gaining phases. Removing the four left turn filters seems an especially egregious example of signal-centric thinking.
Totally agree, the major change is the additional traffic coming down the A38 from the north side, and yet according to that plan will have four potential red lights instead of the current one. I know they will likely be phased to avoid stopping at every one but even so it's hard to see it as an improvement

Herned
Member
Posts: 801
Joined: Thu Jul 20, 2017 09:15

Re: A358 Taunton to Southfields

Post by Herned » Tue Jan 16, 2018 11:55

New consultation open, brochure herehttps://highwaysengland.citizenspace.co ... nedOff.pdf

Three options for the connections to the M5: Orange is the previous option; Blue follows a similar alignment but includes a link to J25, and only south-facing slips to the M5 further south, and Pink, which more closely follows the existing road and links to J25 and has free-flow slips to the M5 further south. The Pink option seems to be pretty much the same as the proposals abandoned last time.

Just noticed the URL for the brochure - must have been a rush job!

User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Tue Jan 16, 2018 12:10

Orange - basically the previous option, with the new roundabout interchange on the M5, though it is at least clear that it won't have connections to the local network there. Astonishingly it would leave a large majority of traffic on the route through Henlade (25k AADT). £366m.

Blue - freeflow fork on the M5, and another limited access freeflow junction for the link to J25. It heads across country creating the most direct route to J25, but as it lacks a direct junction with the A378, 8k traffic will remain in Henlade. £401m.

Pink - similar to blue, but more online and less direct with a dumbbell at the A378. Biggest reduction in traffic in Henlade, to around 5k. £452m.

I think I favour Blue though I can see the advantages of Pink. Amazing to think Orange was the only option in the previous consultation, presumably for cost and development access reasons. In traffic terms it seems a non-starter.

I'm a little disappointed that the furthest offline route, with the full trumpet on the M5, isn't an option (see map). It seemed the only truly long term option in terms of relieving J25.

Image

Herned
Member
Posts: 801
Joined: Thu Jul 20, 2017 09:15

Re: A358 Taunton to Southfields

Post by Herned » Tue Jan 16, 2018 12:59

Where are those costs listed? The brochure doesn't seem to mention costs, and the technical report uses different numbers at 2010 prices...

Richardf
Member
Posts: 1612
Joined: Wed Dec 06, 2006 10:19
Location: Dorchester
Contact:

Re: A358 Taunton to Southfields

Post by Richardf » Tue Jan 16, 2018 13:27

All these plans are nice, but they are slightly missing the point. It's the A358W to/from M5 route that needs improving or separating from Taunton traffic. Do that and the A358W to A358E route through the junction will be improved by default as there will be less competition for road space.
My latest Road Photos https://flic.kr/s/aHsktQHcMB

User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Tue Jan 16, 2018 14:13

Herned wrote:Where are those costs listed? The brochure doesn't seem to mention costs, and the technical report uses different numbers at 2010 prices...
Bottom of the table in the brochure. A footnote clarifies: 'The total estimated cost at 2014 Q1 prices includes scheme preparation costs, purchase of land and the construction of the new road'.

User avatar
RichardA35
Site Manager
Posts: 4609
Joined: Thu Jul 11, 2002 18:58
Location: Dorset

Re: A358 Taunton to Southfields

Post by RichardA35 » Tue Jan 16, 2018 14:50

Richardf wrote:All these plans are nice, but they are slightly missing the point. It's the A358W to/from M5 route that needs improving or separating from Taunton traffic. Do that and the A358W to A358E route through the junction will be improved by default as there will be less competition for road space.
Well the pendulum for this option has swung to planning for the strategic route to the exclusion of nearly everything else, especially in the orange route.
It may be that this is the "point" HE were trying to make and have Somerset to make up the difference to bypass Henlade?

Herned
Member
Posts: 801
Joined: Thu Jul 20, 2017 09:15

Re: A358 Taunton to Southfields

Post by Herned » Tue Jan 16, 2018 15:09

jackal wrote:
Herned wrote:Where are those costs listed? The brochure doesn't seem to mention costs, and the technical report uses different numbers at 2010 prices...
Bottom of the table in the brochure. A footnote clarifies: 'The total estimated cost at 2014 Q1 prices includes scheme preparation costs, purchase of land and the construction of the new road'.
Oh yes, cheers... not exactly hidden then :oops:

User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Tue Jan 16, 2018 16:11

The new TAR has all kinds of weird and wonderful options, including quite a few with north and south M5 freeflow:
A358 Options 1-4 - Copy.PNG
A358 Options 7-11 - Copy.PNG
A358 Options 12-16 - Copy.PNG
The lack of Southfields GSJ is due to the initial options exceeding budget:
All options included a free-flowing connection to the A303 Ilminster
Bypass and associated grade separation of the junction at Southfields
Roundabout. This element of the scheme was estimated to account for
approximately £50m of the estimated out-turn cost and, whilst it did make
a contribution to the realisation of benefits to the scheme, its inclusion
was not essential to fulfilment of the RIS objectives as grade separation
of the Southfields Roundabout could be included in the subsequent
scheme to upgrade the Ilminster Bypass to dual carriageway.
https://highwaysengland.citizenspace.co ... ng-scheme/

SteveA30
Member
Posts: 5320
Joined: Fri May 06, 2005 12:52
Location: Dorset
Contact:

Re: A358 Taunton to Southfields

Post by SteveA30 » Tue Jan 16, 2018 20:25

Well the pendulum for this option has swung to planning for the strategic route to the exclusion of nearly everything else, especially in the orange route.
It may be that this is the "point" HE were trying to make and have Somerset to make up the difference to bypass Henlade?
Good for HE if this is the case, they should not have to cater for local developers or council local plans. They should fit in around the HE plans.

Meanwhile, in Yeovil, work has started to mess up the A3088 past the Lynx Trading Estate. Walk this way please to a new thread..........
Roads and holidays in the west, before motorways.
https://roadhog.shutterfly.com
http://holidayroads.webs.com/

boliston
Member
Posts: 141
Joined: Wed Dec 10, 2014 19:43
Location: Taunton
Contact:

Re: A358 Taunton to Southfields

Post by boliston » Tue Jan 16, 2018 22:12

jackal wrote:......
I'm a little disappointed that the furthest offline route, with the full trumpet on the M5, isn't an option (see map). It seemed the only truly long term option in terms of relieving J25.
Image
Not seen that route before but it looks horrific in terms of destruction of open countryside at the edge of the blackdown hills - I assumed the orange option was being built but now they have "pink" and "blue" also with pink being by far the best in terms of keeping nearer to the existing route and providing a realistic bypass option for henlade, so being a real benefit to the local area rather than just to tourists travelling from london to cornwall. Can't see any benefit to the blue option as too similar to the orange option and little local benefit as too far offline.

Richardf
Member
Posts: 1612
Joined: Wed Dec 06, 2006 10:19
Location: Dorchester
Contact:

Re: A358 Taunton to Southfields

Post by Richardf » Tue Jan 16, 2018 23:06

Is there any merit in a mostly online upgrade, with a northern bypass of Henlade and Ruishton, and meeting the M5 to the north of J25, close to the railway?
My latest Road Photos https://flic.kr/s/aHsktQHcMB

boliston
Member
Posts: 141
Joined: Wed Dec 10, 2014 19:43
Location: Taunton
Contact:

Re: A358 Taunton to Southfields

Post by boliston » Tue Jan 16, 2018 23:21

Richardf wrote:Is there any merit in a mostly online upgrade, with a northern bypass of Henlade and Ruishton, and meeting the M5 to the north of J25, close to the railway?
1) it would impact badly on the river tone and adjacent areas
2) would be very close to existing j25 with inherent weaving dangers
3) would do little to stop local traffic still going through henlade
4) most long distance traffic would be heading south so why take it north?

Richardf
Member
Posts: 1612
Joined: Wed Dec 06, 2006 10:19
Location: Dorchester
Contact:

Re: A358 Taunton to Southfields

Post by Richardf » Tue Jan 16, 2018 23:39

boliston wrote:
Richardf wrote:Is there any merit in a mostly online upgrade, with a northern bypass of Henlade and Ruishton, and meeting the M5 to the north of J25, close to the railway?
1) it would impact badly on the river tone and adjacent areas
2) would be very close to existing j25 with inherent weaving dangers
3) would do little to stop local traffic still going through henlade
4) most long distance traffic would be heading south so why take it north?
Ah right. I see. Just an idea.
My latest Road Photos https://flic.kr/s/aHsktQHcMB

User avatar
A303Chris
Elected Committee Member
Posts: 3178
Joined: Mon Sep 20, 2004 14:01
Location: Reading

Re: A358 Taunton to Southfields

Post by A303Chris » Wed Jan 17, 2018 10:39

I don't know if this has been discussed, but the A358 between the A303 and M5 is currently a county road and after this I take it will become a trunk road.

I therefore assume the 15 miles of A303 / A30 route between the A358 at Southfields and A35 at Honiton will be detrunked afterwards, given apart from holiday weekends flows are low at around 13,000 vehicles per day.

I know Devon are proposing a WSC upgrade between the Devonshire arms and Honiton as detailed here and are saying this is included with the DfTs proposals for small scale improvements to the Blackdowns Hill section.

I have to say that if the rest of the A303 is dualed and this upgrade to the A30 is undertaken, I will still go via the Blackdowns Hills as going via Taunton would add 10 miles to the journey and in my opinion total journey time would be the same
The M25 - The road to nowhere

User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Wed Jan 17, 2018 10:51

The plan is for the Blackdown Hills route to remain trunked. Here's the thread for the improvements on that corridor:

viewtopic.php?f=1&t=36344&hilit=Blackdown

User avatar
wrinkly
Member
Posts: 8370
Joined: Tue Mar 04, 2008 12:17
Location: Leeds

Re: A358 Taunton to Southfields

Post by wrinkly » Wed Jan 17, 2018 11:30

jackal wrote:The plan is for the Blackdown Hills route to remain trunked. Here's the thread for the improvements on that corridor:

viewtopic.php?f=1&t=36344&hilit=Blackdown
Where do you get the information that it will remain trunk?

User avatar
jackal
Member
Posts: 6247
Joined: Tue Jan 08, 2008 23:33
Location: M6

Re: A358 Taunton to Southfields

Post by jackal » Wed Jan 17, 2018 12:09

Some HE document or other. Also note that the A30 proposal is being worked up as a bid for RIS2 cash.

Post Reply