A30 Carland Cross Chiverton Cross

[RichardEvans67]

Just spotted a picture of Carland Cross that I think is recent.

You would probably need a facebook account to see this version :
https://www.facebook.com/ICESouthWest/p ... JFXghqZQzQ

Or googling there is this version, although it's hard to get good resolution :
https://www.google.co.uk/search?q=a30+c ... fke82hTQTM

[RichardEvans67]

by Gaz909909 » Mon Mar 07, 2022 23:57

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.

Although I'm not from the area. I find myself thinking about how much traffic could Truro really generate. I'm also thinking about what you say about it being a lot more busy between May and September.

Isn't this increase mostly because of the increased tourist traffic in the summer. Wouldn't most of this extra traffic be A30 through traffic? So would it really make much difference to the roundabout when this traffic bypasses the roundabout.

I also keep thinking about how much the A30 traffic could currently affect the A390 traffic. I would think only a proportion of the A390 traffic would want A30 west, and a good proportion would need to go onto the roundabout. A heavy A30 west stream would make it much harder for this traffic to enter the roundabout. Hence it would tail back, which would soon block the traffic trying to get to the A30 west. That's all a problem of an at grade junction. I expect removing the A30 through traffic would probably solve the problem, and they would have tested this in traffic models.

I wonder how much the A390 traffic does actually increase during the summer, and how much of this is just that it seems more severe, when the A30 traffic is delaying it and causing it to tail back.

Another way of looking at it. Without the A30 traffic. Then what exactly will be holding up the A390 traffic going onto the roundabout?

[Gaz909909]

Richard, some excellent points.

To your last question, nothing... In the winter. In the summer it's the Newquay traffic weaving from A3075 onto A30 west. You may be bang on in that the A30 going over the roundabout may solve the A390 issue. It's pretty busy on entry to Chivvy most weekday evenings. Don't forget it's an S2. I hope you're right. This 3 way junction sounds interesting though. I'd like to be a fly on that wall.

[Gaz909909]

FYI I'm from Penzance and commuted to Newquay every weekend for years.

[RichardEvans67]

by Gaz909909 » Tue Mar 08, 2022 21:46

This 3 way junction sounds interesting though. I'd like to be a fly on that wall.

It's part of phase 4 of this document. (Warning, this is a very large PDF, so browsing through it is a pain) :
https://infrastructure.planninginspecto ... T%20A1.pdf

This temporary junction is on the new link road from the new Chiverton Cross roundabout to the A390. It serves a temporary link from here to the southern edge of the existing A30. This moves the A30 traffic far enough out of the way to build the new eastbound carriageway.

The reason why this is all rather awkward is that the new A30 will be in a cutting about 2m deep at this point. Obviously to build that, they need to move the traffic out of the way.

FYI. I laboriously copied all the images to PNG images, to make it much easier to browse through them.

[RichardEvans67]

There's also an alternative

https://infrastructure.planninginspecto ... T%20A2.pdf

I wonder if in the alternative it would be better in phase 4 for the A30 westbound to use the Blackwater diversion, instead of the eastbound. I realise this is a longer diversion for west bound than for east bound. My logic is that would mean the temporary junction is only taking A30 eastbound, which would be far easier to merge with the A390 traffic. I think this would make the temporary junction work far better.

[RichardEvans67]

Who knows why this has only recently been uploaded.

https://www.youtube.com/watch?v=opvfVzDJykU

[Gaz909909]

Cracking video Richard. A nice find. Yes a little old but you can really see the new line.

They are really cracking on with it!

[RichardEvans67]

by Gaz909909 » Mon Mar 14, 2022 21:36

Yes a little old but you can really see the new line.

Taking another look. I noticed that towards the end (About 7:08). I noticed two sets of two trenches (4 in total near the bottom right). Pretty sure these must be for the foundations for the two new bridges over the new Chiverton Cross Roundabout. Then I noticed that you can make out the circular shape of the roundabout.

[Gaz909909]

Yes I saw that. You're 100% correct there. I'm just surprised it's not a cheapo dumbbell!

[A320Driver]

Yes I saw that. You're 100% correct there. I'm just surprised it's not a cheapo dumbbell!

It was a dumbbell in the original design, thankfully changed to a roundabout GSJ after consultation and NH realising it would be totally overwhelmed from day one.

[Gaz909909]

Yes I saw that. You're 100% correct there. I'm just surprised it's not a cheapo dumbbell!

It was a dumbbell in the original design, thankfully changed to a roundabout GSJ after consultation and NH realising it would be totally overwhelmed from day one.

If someone from NH stood on that roundabout for more than 10 minutes any weekday early evening or any day in the summer, they wouldn't have wasted their time.

[BF2142]

The new Carland Cross junction is a basic DB junction. Hope it's up to the job.

[Gaz909909]

My understanding is that it's a single roundabout GSJ. Check page 7.

https://infrastructure.planninginspecto ... ITIONS.pdf

[crowntown100]

My understanding is that it's a single roundabout GSJ. Check page 7.

https://infrastructure.planninginspecto ... ITIONS.pdf

BF2142 was referring to Carland Cross, not Chiverton.

The new Carland Cross junction is a basic DB junction. Hope it's up to the job.

The main different between the two is that there is one dominant flow at Carland Cross (A30 wb to A39 sb, and visa versa), where as there are two A roads and a busy B road connecting at Chiverton Cross. Carland is also laid out so that there are no conflicts between A30 and A39 movements, which will help. It might be more of a struggle getting out of the (to be extended) B3285 at peak times, though.

I'd be interested to see whether the flows will change significantly from the A3075 to Newquay to A30/A3076, with a lot more of the route being dual carriageway, but that remains to be seen.

As an aside, Chiverton Cross is progressing with the bridge piers now in place, much like the bridge at Chybucca junction. They have also started laying out the routes for the diversions around the works now, and have started to level the ground on sections of the route so they are probably close to laying the foundations of the main dual carriage between Chiverton Cross and Chybucca. I kind of wish I had a drone to be able to take some photos, but I digress.

[adam 1972]

Another thing I noticed today is the embankment work at Chybucca is really progessing now on both sides of the new bridge and the northern side of the A30, it really does show the difference in height between the existing A30 and where the northern roundabout is going.

[multiraider2]

I'd be interested to see whether the flows will change significantly from the A3075 to Newquay to A30/A3076, with a lot more of the route being dual carriageway, but that remains to be seen.

I'd certainly be considering changing routes if going between Penwith and Newquay say and where I would have taken the A3075. That is unless I'm going for cider/ice cream at Penhallow/Callestick en-route or the dualling just puts too much Newquay traffic on the A3076/A3058.

I'd say that the real test is going to be west of Camborne. Clearly the through-flow will be increased and that's got to put extra pressure on the remaining non-dualled section and Loggans Moor in particular.

[Gaz909909]

My understanding is that it's a single roundabout GSJ. Check page 7.

https://infrastructure.planninginspecto ... ITIONS.pdf

BF2142 was referring to Carland Cross, not Chiverton.

The new Carland Cross junction is a basic DB junction. Hope it's up to the job.

The main different between the two is that there is one dominant flow at Carland Cross (A30 wb to A39 sb, and visa versa), where as there are two A roads and a busy B road connecting at Chiverton Cross. Carland is also laid out so that there are no conflicts between A30 and A39 movements, which will help. It might be more of a struggle getting out of the (to be extended) B3285 at peak times, though.

I'd be interested to see whether the flows will change significantly from the A3075 to Newquay to A30/A3076, with a lot more of the route being dual carriageway, but that remains to be seen.

As an aside, Chiverton Cross is progressing with the bridge piers now in place, much like the bridge at Chybucca junction. They have also started laying out the routes for the diversions around the works now, and have started to level the ground on sections of the route so they are probably close to laying the foundations of the main dual carriage between Chiverton Cross and Chybucca. I kind of wish I had a drone to be able to take some photos, but I digress.

I must be tired! Yeah at Carland the A39 is not that busy. Honestly more traffic goes to the Shell garage from that junction! Yep the dumbbell is perfect there.

[Gaz909909]

I'd be interested to see whether the flows will change significantly from the A3075 to Newquay to A30/A3076, with a lot more of the route being dual carriageway, but that remains to be seen.

I'd certainly be considering changing routes if going between Penwith and Newquay say and where I would have taken the A3075. That is unless I'm going for cider/ice cream at Penhallow/Callestick en-route or the dualling just puts too much Newquay traffic on the A3076/A3058.

I'd say that the real test is going to be west of Camborne. Clearly the through-flow will be increased and that's got to put extra pressure on the remaining non-dualled section and Loggans Moor in particular.

I'm pretty sure they were going to hamburger that junction? Hayle bypass is madness in the summer. The tourists have got stuck in queues and have attempted to do u turns, often leading to very serious accidents.

https://www.cornwalllive.com/news/cornw ... 799029.amp

[RichardEvans67]

by Gaz909909 » Fri Mar 25, 2022 21:34

I'm pretty sure they were going to hamburger that junction?

They were, but I haven't read about it for a long time now, so I don't know how it's progressing.
viewtopic.php?f=1&t=41911
It seemed very expensive for what it is.