A30 Carland Cross Chiverton Cross

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RichardEvans67
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Re: A30 Carland Cross Chiverton Cross

Post by RichardEvans67 »

by Richardf » Mon Jun 06, 2022 21:56

Since the old road is being kept to serve local traffic and reduce need for junctions, why even have a junction at Chybucca at all? Couldn't the traffic that would use the west facing sliproad just use the current A30 down to Chiverton Cross?
I think it's a case of where do you draw the line. At what point are the traffic levels high enough to justify a junction. I expect they would have done pretty extensive traffic modeling at some point, and we probably don't know the detailed results.

The idea of no Chybacca junction crossed my mind. However, if you look at the B road from Turo, it is already going vaguely in that direction. So there is probably a lot of traffic wanting to go that way. That B road is going the wrong way for Carland, so I would expect traffic levels that way to be a lot lower.

Also as Jakal said. West-facing skips at Chybacca will relieve Chiverton Cross junction of that traffic. I'd add that Chiverton Cross will still be a pretty busy junction. So taking traffic away from it will be an advantage. That must go a long way to justify the slips at Chybacca.

Edit :
I may have already said this. I expect the new local route (Existing A30), will become a good drive once all the A30 through traffic is removed from it.
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Re: A30 Carland Cross Chiverton Cross

Post by Sam S »

Someone was asking for the plans, these are the most up to date: https://infrastructure.planninginspecto ... 206%29.pdf

For those are interested these are the reasons for the west facing only slip roads at Chybucca (with traffic numbers), the underpass at Chiverton, and the lack of A390 slip road (starts on documment page 60 or PDF page 67): https://infrastructure.planninginspecto ... REPORT.pdf
From what I've observed a lot of traffic uses Chybucca from the West to access Truro avoiding the congestion around Threemilestone, Treliske Hospital and Highertown. But Truro East traffic uses Carland and Perranporth traffic uses Boxheater (for East) or Chiverton (for West). Would only be useful for Shortlanesend.

8.2 Summary of matters raised that did not result in changes and
why

8.2.1 As summarised in section 8.1, changes to the design of the scheme since
statutory consultation have been influenced by a combination of factors, including
suggestions and matters raised by the public, PILs and stakeholders in response
to the consultation. However, not all suggestions or matters raised could be
accommodated within the design of the scheme, taking into account other
constraints such as environmental impacts, cost of the scheme, land required and
engineering and safety standards.
8.2.2 This section summarises key issues or suggestions raised in response to
consultation that did not subsequently result in a change to the design of the
scheme. It highlights those issues and suggestions that were raised most
frequently; a response from Highways England on all individual matters raised
and suggested changes is provided in section 8.4 to 8.7 of this chapter.

Chiverton Cross WCH Connection
8.2.3 A key issue raised during public consultation was the impact of the relocated
Chiverton junction on WCH connectivity. It was felt by members of the public,
interest groups and statutory consultees that the provision for WCH at the new
Chiverton junction is inadequate, specifically in relation to the proposed
requirement for WCH users to add 1.5km to the journey in order to gain access
between the B3277 from St Agnes and the A390 to Truro. The impact of this on
commuters between St Agnes and Truro, as well as in terms of safety and
encouraging sustainable travel, was found to be unacceptable by many
respondents. It was suggested that a WCH crossing is required at the site of the
existing Chiverton junction, following the ‘desire line’ between the B3277 and the
A390.
8.2.4 Highways England considered the feedback regarding the WCH crossing at
Chiverton Cross and determined that the provision of a crossing at the location
stipulated by respondents would not be feasible due to the impacts of including
the crossing on the project and construction programme. The preferred location of
a cycle bridge is further constrained by the potential effects a crossing in this
location could have on the World Heritage Site.
8.2.5 Although the preferred WCH connection location has been deemed unfeasible for
inclusion in the DCO submission, Highways England has committed to delivering
improved WCH connectivity through the addition of a proposed underbridge
approximately 1km from the preferred ‘desire line’ location stated by respondents.
This underpass [identified as PR2] is detailed in Chapter 12 - People and
Communities of the Environmental Statement (Volume 6, Document Reference
6.2,) and in the PRoW Management Plan (Volume 6, Document Reference 6.4,
ES Appendix 16.1 Outline CEMP Annex P) and in the Public Rights of Way
Plan (Volume 6, Document Reference 6.3, ES Figure 12.4). New off-carriageway
connections are also provided between the realigned B3277 and the realigned
A3075; and between the realigned A390 and the existing A30. These changes
mean that WCH users will be able to navigate Chiverton without travelling on the
main carriageway.
A30 Chiverton to Carland Cross | HE551502 Highways England
HA551502-ARP-GEN-SW-RP-ZH-000008 | C01, A3 Page 61 of 491

Segregated A390 slip roads
8.2.6 Concern was raised in response to consultation that the design of Chiverton
junction would result in congestion on the A390 and on the main carriageway of
the new A30. Objection was also raised to the additional 1.5km distance required
to travel from the A390 to Chiverton, due to the eastern relocation of the junction.
It was suggested that additional slip-roads would be needed, particularly a westbound segregated slip-road onto the A30 from the A390.
8.2.7 Highways England has considered the need for an additional slip road in this
location, including west-bound from the A390 onto the A30. Traffic modelling
(using the established SATURN modelling software) has been undertaken during
the development of the scheme, as detailed in the Transport Report (Volume 7,
Document Reference 7.4), The modelling shows that there would be no
significant harmful impacts overall in relation to congestion on the A390 as a
result of the scheme.
8.2.8 Furthermore, a detailed modelling assessment of the proposed Chiverton junction
(using Junctions 9 software) shows that the scheme would not result in significant
impacts such that would lead to queuing and congestion on the new A30. The
assessment shows that the new Chiverton design would significantly reduce
queues on the A390 in comparison to a ‘Do Minimum’ scenario (in which the
proposed scheme is not implemented and the existing A30 remains in its current
form). Therefore, Highways England consider that there is not sufficient demand
for the provision of additional segregated slip roads in this location.
8.2.9 Beyond demand, there are additional constraints to this aspect of the design that
Highways England has taken into consideration. First, under the DMRB, there is a
minimum required spacing distance of 450m between consecutive merges, such
as on-slips for Chiverton junction and the A390. This is required in order to
provide adequate space for vehicles to safely enter and exit the main
carriageway. A second constraint is the close proximity of the World Heritage Site
boundary, which limits the potential alignment and position that the on-slip would
be able to take within the design and safety standards.
8.2.10 Given the lack of forecast requirement and cost implications, the safety and
engineering constraints, and potential impact, Highways England has determined
that the provision of the suggested west-bound on-slip for the A390 should not be
included in the scheme.

Chybucca, east facing slip roads
8.2.11 A key concern raised at statutory consultation, as well as in previous nonstatutory consultation and engagement, was the non-provision of east facing slip
roads at Chybucca junction. A significant number of respondents to the statutory
consultation raised concerns on the impacts that the lack of east facing slips
would have on connectivity, traffic through local roads (rat-running) and
congestion, with some respondents querying the design would represent good
value for money or undermine the principle of the scheme.
8.2.12 During non-statutory consultation on the scheme in late 2016, the lack of east
facing slip roads at Chybucca was raised as a concern. As detailed in the
Scheme Assessment Report (Volume 7, Document Reference 7.6), Highways
England considered this issue in response to the concerns raised at consultation
A30 Chiverton to Carland Cross | HE551502 Highways England
HA551502-ARP-GEN-SW-RP-ZH-000008 | C01, A3 Page 62 of 491
and concluded that the predicted traffic flows did not justify the provision of east
facing slip roads at this location as part of the scheme.
8.2.13 Following the Preferred Route Announcement (PRA) in 2017, Highways England
has further assessed the provision of east facing slip roads through additional
traffic modelling. The traffic model was further developed and includes additional
local roads used for rat running. The model demonstrates that the number of
vehicles using the east facing slip roads remains low in comparison to that of
those using the west facing slip roads. The model shows that by 2038, the
demand for east facing slip roads would be 1,764 vehicles per day (528 east
facing on-slip and 1,236 east facing off-slip), whilst demand for west facing slip
roads would be 11,322 vehicles per day (4,799 west facing on-slip and 6,523
west facing off-slip).
8.2.14 Beyond consideration of demand for east facing slip roads, there are other
aspects that would also need to be considered, such as: construction costs,
environmental impacts, increased land take, which would be significant in this
location given the extent of additional earthworks, cuttings and embankments that
would be required to construct the slip roads.
8.2.15 To summarise, the introduction of east facing slip roads has been reviewed by
Highways England following both non-statutory and statutory consultation, and
the decision to provide west facing slip roads only at Chybucca is still supported.
Given that future demand is predicted by the traffic modelling to be low, east
facing slip roads would not address the specific issues of congestion, safety,
network reliability and capacity on the existing A30.
8.2.16 Further detail on the traffic modelling undertaken in this assessment is provided in
the Transport Report (Volume 7, Document Reference 7.4) and details of the
environmental assessment are provided in the Environmental Statement
(Volume 6, Document Reference 6.2).
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jackal
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Re: A30 Carland Cross Chiverton Cross

Post by jackal »

Thanks for that, which certainly shows why they're not providing east-facing slips at Chybucca:
Sam S wrote: Wed Jun 08, 2022 12:30 The model shows that by 2038, the
demand for east facing slip roads would be 1,764 vehicles per day (528 east
facing on-slip and 1,236 east facing off-slip), whilst demand for west facing slip
roads would be 11,322 vehicles per day (4,799 west facing on-slip and 6,523
west facing off-slip).
The stuff about the A390 is much less convincing. The strange terminology ('segregated slip roads') makes me wonder if they really understood what was being requested. The consecutive merge spacing of 450m is a relevant point but the slip off the A390 could be instead of the west-facing onslip at the new roundabout, rather than in addition. Furthermore, the usual line that the proposed junction is within capacity is irrelevant when the complaint is with the indirectness of the route (and hence journey times, fuel consumption, emissions, etc) rather than capacity.
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Re: A30 Carland Cross Chiverton Cross

Post by Herned »

It is slightly surprising that the slips at Chybucca are west-facing. That, as well as the movement north/east of the junction with the A390 will surely make the B3284 a more attractive option for Truro city centre which these schemes normally try to avoid.

The argument about a possible cycle bridge at the old junction site affecting the WHS seems pretty disingenous, considering there is already a dual carriageway and a McDonalds there
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Mapper89062
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Re: A30 Carland Cross Chiverton Cross

Post by Mapper89062 »

I would have thought they could have avoided the detour / NMU access problems by just putting the GSJ further south, perhaps not right at the current roundabout as there the road is online, but maybe about halfway between the two locations? There's plenty of space for it, and while a longer link to the A3075 is needed, the other ones become shorter to make up for it.
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Re: A30 Carland Cross Chiverton Cross

Post by Richardf »

Think I understand about Chybucca now. The report clarifies things somewhat. Thanks.

Re: The A390 issue at Chiverton X, the solution to A390 traffic effectively doubling back on itself when going wb could have been to make the WB onslip longer and partially 2 way so that it could be combined with the A390 link road. Add a smaller roundabout near where the current roundabout is and A390 wb traffic could avoid the main Chiverton GSJ entirely. Or would that not work with the terrain and surrounding property?
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

It will be interesting to see what gets signed at the new Chybucca Junction as it would look a bit odd if Truro (Cornwall's only city) is signed off a fast modern dual carriageway onto a 'B Road'. Here are some of my latest pictures taken from the soon to be removed (and replaced) Tolgroggan Overbridge near Zelah.
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New bridge (under construction)
New bridge (under construction)
The view near Zelah
The view near Zelah
The view from the Tolgroggan Overbridge
The view from the Tolgroggan Overbridge
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

My latest pictures of the construction of the new A30 and Chybucca Junction.
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Chybucca Junction (construction)
Chybucca Junction (construction)
A30 construction and temporary route around the construction site
A30 construction and temporary route around the construction site
A30 construction
A30 construction
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

The overbridge (under construction) at the new Chybucca Junction
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Overbridge (under construction) at Chybucca Junction
Overbridge (under construction) at Chybucca Junction
Gaz909909
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Re: A30 Carland Cross Chiverton Cross

Post by Gaz909909 »

Fab photos - especially of the Tolvaddon overbridge. Thanks for the effort.

You know, in regards to Chivvy X, that A390 solution is awful. It's such a detour now. It might actually be quicker to use the Chubucca westbound slips to get to Truro anyway!!
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

The B3284 from the A30 at the new Chybucca Junction certainly shouldn't be a recommended route to Truro as it goes through the village of Shortlanesend and it doesn't link to the Park and Ride. Having said that I have often found it to be at least 15 minutes quicker than the A390.
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crowntown100
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Re: A30 Carland Cross Chiverton Cross

Post by crowntown100 »

jackal wrote: Wed Jun 08, 2022 13:19 The stuff about the A390 is much less convincing. The strange terminology ('segregated slip roads') makes me wonder if they really understood what was being requested. The consecutive merge spacing of 450m is a relevant point but the slip off the A390 could be instead of the west-facing onslip at the new roundabout, rather than in addition. Furthermore, the usual line that the proposed junction is within capacity is irrelevant when the complaint is with the indirectness of the route (and hence journey times, fuel consumption, emissions, etc) rather than capacity.
I raised this at the first public consultation with them 5 years ago now, and trying to get through to them to add a segregated left turn at the roundabout was painful. They seemed to think, as the report suggests, that I (and I assume others, but I've read a few things in that report that I remember raising) meant a separate slip road, when I meant a filter lane like the current roundabout has, but it would filter onto the sliproad instead of the main carriageway.

I also have to say that, on a plan, it looks like a long detour. Driving past the new roundabout on the A3075, IMHO it really doesn't feel that far.
roadphotos wrote: Wed Jun 08, 2022 21:45 The B3284 from the A30 at the new Chybucca Junction certainly shouldn't be a recommended route to Truro as it goes through the village of Shortlanesend and it doesn't link to the Park and Ride. Having said that I have often found it to be at least 15 minutes quicker than the A390.
Watching the flythough, that suggests that the junction will be signposted as Truro, Shortlanesend, B3284.

Great photos, by the way. I've been meaning to get up there myself but just haven't had a chance. Have you noticed the fact you have to move across lanes as you approach the roundabout at Chybucca to stay on the A30 when heading w/bound? They've also played around with the lanes at Chiverton Cross heading w/bound, and they keep catching me out!
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

Chiverton is awful anyway, I'll be glad to see it go. I've lost count of the amount of times I've been cut up by drivers on the roundabout even though I was in the correct lane for my exit.
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Re: A30 Carland Cross Chiverton Cross

Post by Gaz909909 »

I'm hoping that it will actually be quicker for A390 to A30 westbound traffic even though it's further, as they are hopefully not queuing at the roundabout. They still have to give way to A3075 traffic heading west, but it shouldn't be as much. Let's see...
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Re: A30 Carland Cross Chiverton Cross

Post by RichardEvans67 »

by roadphotos » Wed Jun 08, 2022 18:44

Here are some of my latest pictures taken from the soon to be removed (and replaced) Tolgroggan Overbridge near Zelah.
Thanks for the pictures.

A video I found the other week briefly showed that big bridge beam at Tolgroggan. Although your pictures show it in more detail. Also your pictures show what looks like some bride peers (columns) being constructed. I wonder if they are using the same approach as at Chybacca, constructing the peers, and then putting retaining walls in front of them.
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Re: A30 Carland Cross Chiverton Cross

Post by RichardEvans67 »

by Richardf » Wed Jun 08, 2022 18:35

Re: The A390 issue at Chiverton X, the solution to A390 traffic effectively doubling back on itself when going wb could have been to make the WB onslip longer and partially 2 way so that it could be combined with the A390 link road. Add a smaller roundabout near where the current roundabout is and A390 wb traffic could avoid the main Chiverton GSJ entirely. Or would that not work with the terrain and surrounding property?
I'm thinking there could be another issue with that idea. Traffic going from the main roundabout, on to the A30 wb. Would hold up traffic from Truro, wanting to turn right at the smaller roundabout. The result could be tailbacks on the A390.

I don't know how much of a problem this could be, but they may have done the traffic modeling for that.
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Re: A30 Carland Cross Chiverton Cross

Post by IAN »

A short video showing the approach to the temporary roundabout in which it is suggested that the road markings are incorrect. it seems that a right-hand arrow is needed rather than a straight-ahead arrow. https://www.youtube.com/watch?v=n-CJk7s ... chardPratt
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Re: A30 Carland Cross Chiverton Cross

Post by adam 1972 »

Just driven through Chybucca & they now have the bridge beams in place.
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Re: A30 Carland Cross Chiverton Cross

Post by RichardEvans67 »

by IAN » Fri Jun 10, 2022 15:20

A short video showing the approach to the temporary roundabout in which it is suggested that the road markings are incorrect. it seems that a right-hand arrow is needed rather than a straight-ahead arrow. https://www.youtube.com/watch?v=n-CJk7s ... chardPratt
Yes, the road to perranporth is effectively a right turn. So a right turn arrow for that lane would make more sense. Although is it worth a road closure to change the road markings? I suppose confusion could lead to an accident or two, so perhaps it would be worth it.

Edit : I noticed that the same seems to be true for the opposite direction,
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Re: A30 Carland Cross Chiverton Cross

Post by roadphotos »

Chybucca Junction construction site (today)
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Chybucca Junction (construction site)
Chybucca Junction (construction site)
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