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I haven't seen whether this is correct or not so this is purely speculation, but I imagine that they will build what will become the LARs over the bridge and divert traffic to use the new junction, less the sliproads, so that they can complete tie in works and building the new road under the bridge without disrupting the traffic still on the A30.
It looks like that's part of the plan, but I think that what happens before that is more interesting. The roundabouts either side of the new bridge will be well above the current road level. So the traffic needs to be diverted to be able to construct them.
They have already implemented a temporary realignment of the B3284, to allow the south roundabout and it's access ramps to be built. They would probably do something similar with the A30, to allow the building of the north roundabout and it's access ramps. Although, on the pictures I have managed to find, there wasn't much sign of that. Perhaps it wasn't worth the extra resources to build both realignments at once, so I wonder if they are now building the A30 realignment.
RichardEvans67 wrote: ↑Mon Feb 07, 2022 05:42
It looks like that's part of the plan, but I think that what happens before that is more interesting. The roundabouts either side of the new bridge will be well above the current road level. So the traffic needs to be diverted to be able to construct them.
They have already implemented a temporary realignment of the B3284, to allow the south roundabout and it's access ramps to be built. They would probably do something similar with the A30, to allow the building of the north roundabout and it's access ramps. Although, on the pictures I have managed to find, there wasn't much sign of that. Perhaps it wasn't worth the extra resources to build both realignments at once, so I wonder if they are now building the A30 realignment.
I will be very interested to see how they implement this, there is quite a height difference between the existing A30 and the bridge.
It looks like there is some embankment work going on around where the southern roundabout will be built, and a lot of work going on to the north.
According to the plans the existing A30 just west of Chybucca is to be re-aligned slightly to form part of the LAR.
It looks like there is some embankment work going on around where the southern roundabout will be built, and a lot of work going on to the north.
Although, I think it can be hard to know what is earthworks, and what is just keeping soil in good condition, the be reused nearer the end of the scheme.
I was a bit confused when he said he was at Boxheater. As Boxheater is far enough away from the new D2, so that I didn't expect to see anywhere near that much works there. However, I soon realised that actually it all seemed to be Chybacca right from the start. So I'm pretty sure he made a mistake calling it Boxheater.
Well, I will say that a poor video is better than no video at all.
Yeah, it confused me as well until I watched it again, I've have posted a comment and pointed out his mistake.
I wish he'd invest in a decent camera, but still very interesting videos, hope he keeps them coming.
On Sentina Playground, looking at Chybacca, on 18th Feb 2022. The northern edge of the roadworks look a different colour. The resolution is too poor to be sure what this is, but I think it's probably for the temporary realignment of the A30. To take traffic away from the North Roundabout site.
RichardEvans67 wrote: ↑Thu Feb 24, 2022 17:03
Just to mention something.
On Sentina Playground, looking at Chybacca, on 18th Feb 2022. The northern edge of the roadworks look a different colour. The resolution is too poor to be sure what this is, but I think it's probably for the temporary realignment of the A30. To take traffic away from the North Roundabout site.
,
I noticed that too, it looks like part of it could be the new B3284 when comparing the image to the plans, I have downloaded all the clear Sentinel images & when flicking through them it looks like a lot going on in that area in a short space of time, the bit of grey extending to the east is more than likely to be part of the temporary alignment.
adam 1972 wrote: ↑Fri Feb 25, 2022 15:43
I noticed that too, it looks like part of it could be the new B3284 when comparing the image to the plans, I have downloaded all the clear Sentinel images & when flicking through them it looks like a lot going on in that area in a short space of time, the bit of grey extending to the east is more than likely to be part of the temporary alignment.
I would back that it is a temporary alignment. They had started to knock through the hedge between the A30 and that grey area. From memory, the northern of the two new roundabouts at Chybucca is on the line of the current A30, so that needs moving before they can build the new roundabout.
crowntown100 wrote: ↑Sun Feb 06, 2022 16:55
They did the same at Temple when that was being built. I guess the piles hold the weight of the bridge, and the retaining wall is just there for... well, retaining
Just to update that they have filled in behind the retaining walls now. I can't imagine it will be too long before beams are lifted in for the bridge.
They have also started building the piles for the foundations of the bridges for the new Chiverton Cross junction, with the NMU underpass already built to the south west of the junction.
From memory, the northern of the two new roundabouts at Chybucca is on the line of the current A30, so that needs moving before they can build the new roundabout.
Correct.
I'd add that new roundabout will be well above the exiting A30. So no chance of building that with the traffic still using the old A30.
Just to update that they have filled in behind the retaining walls now. I can't imagine it will be too long before beams are lifted in for the bridge.
They have also started building the piles for the foundations of the bridges for the new Chiverton Cross junction, with the NMU underpass already built to the south west of the junction.
Good stuff .
A video I posted above said they had been backfilling around that new underpass at Chiverton.
Just drove from Chiverton to Chybucca and through Shortlanesend, it's all looking very different now.
The B3284 Perranporth turn off is now blocked with concrete barriers, the road has been narrowed down & now a new filter lane to turn right onto the B3284 south, and looks like there is no right turn from the B3284 onto the A30 east.
It does to me look like there will be a temporary alignment to the north in the next few weeks, hopefully that chap will do a new video soon.
A30 Chiverton to Carland Cross - Temporary additional 48 hour 24/7 closure B3284 North at Chybucca
Costain, on behalf of National Highways, is working on the A30 Chiverton to Carland Cross road improvement scheme and will be temporarily closing the B3284 North, for an additional 48 hours due to weather related issues, for drainage surfacing and other works to take place.
The B3284 North will continue to be temporarily closed for all through traffic from the A3075 to Chybucca, except for residents, for an additional 48 hours 24/7, from Saturday the 5 March 2022 at 6:00am (06:00hrs) until Monday the 7 March at at 5:00am (05:00hrs).
It will fully reopen on Monday the 7 March at 5:00am (05:00hrs)
The existing diversion route will remain effective until Monday the 7 March at 5:00am (05:00hrs) 2022.
This diversion affects very little drivers. Especially at the weekend. There may be the odd emmit going to the cider farm, but really that's probably it, especially as it's out of season.
It will be interesting to see if the A30 bridge / roundabouts diversion is in place before the summer, otherwise it's going to be horrendous for West Cornwall w/bound traffic. Chivvy (and the lead up) is bad enough as it is in the summer.
It will be interesting to see if the A30 bridge / roundabouts diversion is in place before the summer, otherwise it's going to be horrendous for West Cornwall w/bound traffic. Chivvy (and the lead up) is bad enough as it is in the summer.
I'm not sure whether you are talking about Chiverton or Chybucca. Either way, I don't see how it makes much difference.
At Chybucca, the A30 will probably be the next road to be diverted, but the existing A30 would still be in use until the diversion is ready.
At Chiverton. The 1st road to be diverted would probably be the A3075. But likewise, the old route would be in use until the diversion is ready.
Yes, my concerns about any of the roads at Chybucca are light. Traffic at this time of year is non existent. For those of you that live in West Cornwall (I presume Crowntown does?), you'll know that Chiverton X is the beating heart of getting anywhere in Cornwall. It has been hugely under developed for years. My concern is not traffic numbers now. Its from May. A3075 again is very light at this time of year (who needs to get from Newquay to Camborne /Redruth anyway?) but from the summer the A30 / A390 and A3075 are critical arteries for tourists. They all meet in one place and as it is most locals are scared witless of Chivvy. The whole thing is going to be horrific from May - September. Personally, I would take the A39 from Mitchell to Truro, then up the A390 to Threemilestone, then sneak through Chasewater to Redruth. Old school.
My point is that any A30 / A3075 diversions should be done in winter and the duff local roads (like anything from Chybucca) can be done in the summer. I'm not sure this has been planned with tourists in mind. They will regret that.
That being said, I'm not a huge fan of the new Chiverton X GSJ. Yes it's a GSJ (wow!) but a huge amount of the NW bound A390 traffic goes from Truro to A30 westbound. Traffic build up there is pretty bad, as Treliske is just down the road. With the whole junction now skewed to the east, they need to retain the original w/bound slip lane or that Truro traffic is still going to pile up, just like it did previously, due to Newquay traffic from A3075 weaving in. It's an opportunity lost. Maybe I'm wrong and it will be wonderful, like A39 in Indian Queens, but I'm not sure.
That being said, I'm not a huge fan of the new Chiverton X GSJ. Yes it's a GSJ (wow!) but a huge amount of the NW bound A390 traffic goes from Truro to A30 westbound. Traffic build up there is pretty bad, as Treliske is just down the road. With the whole junction now skewed to the east, they need to retain the original w/bound slip lane or that Truro traffic is still going to pile up, just like it did previously, due to Newquay traffic from A3075 weaving in. It's an opportunity lost. Maybe I'm wrong and it will be wonderful, like A39 in Indian Queens, but I'm not sure.
Bear in mind that removing the A30 through traffic from the Chiverton X roundabout, should make the whole roundabout work a whole lot better. I think you will find that other traffic movements currently cause congestion, because of the A30 traffic delaying those movements. Take away the A30 through traffic, and those traffic queues would tend to melt away.
I assume they would have done plenty of traffic modeling to see how well the new junction will work. I suppose if at some point in the future the Truro to A30 west traffic does turn out to become an issue again. They could add a new free flow lane to the new chivy roundabout.
Edit:
In the early 90s, my job was IT support in an engineering firm, working on road schemes. About 1/2 my time was dealing with data from their traffic modeling. They had had on the road surveys, where they stopped people, to find out where they were traveling to and from. (Coincidently a year before I got that job, I was stopped by one of their surveys). So they had traffic numbers for all the main journeys. For each possible scheme they designed, they used a computer model to predict traffic levels for all the roads and movements. Hence they found out whether the scheme would work. I assume they would go to at least as much effort today. So I would expect they have calculated whether the scheme designed would leave any problems.
Last edited by RichardEvans67 on Sun Mar 06, 2022 08:17, edited 6 times in total.
I'd add that I don't think the initial A3075 diversion at Chiverton will make any significant difference. It's basically just another single carriageway on a different alignment.
What does concern me a bit, is the later stages of a traffic management plan I saw. It uses a temporary 3 way junction for the A390, and the A30 west. I can see that junction struggling to cope with the high levels of traffic. Although coming up with better ideas is hard. A suggestion I read was to utilise the Blackwater diversion route (only in one direction). Although I didn't understand all the details, that could be a less bad way of doing it.
I also have another possible plan of my own. Although I don't have access to all the information, so my plan might not work.
Thanks for your thoughts Richard . I appreciate your view. I'd pretty much agree, although will emphasise the point that this junction carries at least 3x more traffic between May and September.
And again, my point still stands that if, in the planning, they have not considered this, it's going to be a mess.
If you're right and a temp three way junction is used, it will be busy. But. If that junction happens to land in the summer it will be a disaster.
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