A38 Derby Junctions

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jackal
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Re: A38 Derby Junctions

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Letter from DfT requesting info and with some details of the redetermination process:

https://infrastructure.planninginspecto ... letter.pdf
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Re: A38 Derby Junctions

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The redetermination process is rumbling along with some banal but procedurally necessary documents published.

https://infrastructure.planninginspecto ... junctions/
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Re: A38 Derby Junctions

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"Derby roundabout [Markeaton] a crash hotspot with incidents 'more or less every day'"

www.derbytelegraph.co.uk/news/derby-new ... ts-6031222
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Re: A38 Derby Junctions

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DCO has faced a legal challenge.
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Re: A38 Derby Junctions

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KILLER KNIGHT wrote: Sat Feb 25, 2023 14:59 DCO has faced a legal challenge.
The DCO was quashed in 2021. Detailed design for the scheme is complete and NH are just waiting for the SoS to redetermine it. There has been no recent legal action so far as I know.
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Re: A38 Derby Junctions

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jackal wrote: Sun Feb 26, 2023 09:47
KILLER KNIGHT wrote: Sat Feb 25, 2023 14:59 DCO has faced a legal challenge.
The DCO was quashed in 2021. Detailed design for the scheme is complete and NH are just waiting for the SoS to redetermine it. There has been no recent legal action so far as I know.
That’s good to hear. :msnthumbsup:
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Re: A38 Derby Junctions

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jackal wrote: Sun Feb 26, 2023 09:47
KILLER KNIGHT wrote: Sat Feb 25, 2023 14:59 DCO has faced a legal challenge.
The DCO was quashed in 2021. Detailed design for the scheme is complete and NH are just waiting for the SoS to redetermine it. There has been no recent legal action so far as I know.
I confused this scheme with the A57 Link Roads scheme.
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Re: A38 Derby Junctions

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Re: A38 Derby Junctions

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Ishtaria1980 wrote: Fri Aug 18, 2023 15:47 The DCO has been regranted https://www.bbc.co.uk/news/uk-england-d ... 543260.amp
Let's hope the six week period for legal challenges is final and after that TAN or any other stupid anti road group can't use delaying tactics to halt the start of construction.
How would you like your grade separations, Sir?
Big and complex.
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Re: A38 Derby Junctions

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Truvelo wrote: Fri Aug 18, 2023 21:33 Let's hope the six week period for legal challenges is final and after that TAN or any other stupid anti road group can't use delaying tactics to halt the start of construction.
Reading the story, it does appear that the action group will mount a legal challenge in the next 6 weeks.
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Re: A38 Derby Junctions

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Don’t dignify them with any credit, it’s just a desperate delaying tactic. And they have to present new arguments, not rehashed old ones.

I really struggle to see why their claim that the junctions programme will increase traffic has any merit to it.
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Re: A38 Derby Junctions

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Berk wrote: Fri Aug 18, 2023 22:10 Don’t dignify them with any credit, it’s just a desperate delaying tactic. And they have to present new arguments, not rehashed old ones.

I really struggle to see why their claim that the junctions programme will increase traffic has any merit to it.
Interesting observations have been made over time on the addition of capacity to roads, in that they induce demand, as the additional capacity encourages people to drive instead of using alternative methods of travel such as public transport or cycling under the presumption that the additional capacity means that traffic will flow faster, which fills up the road again, and the cycle continues. That's not to say that adding capacity to roads can be incredibly useful, especially over the long-term, but once adding an extra lane stops having any long-term effect on congestion, then it's time to rethink the way we go about relieving roads of congestion.
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Re: A38 Derby Junctions

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But this is not part of the urban road network, but a trunk road. And it’s not really about adding capacity, just ensuring the local part of the network runs smoothly, with GSJ’s.

The campaigners are basically saying they hate GSJ’s, or don’t understand that that’s not really adding mainline capacity.
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Re: A38 Derby Junctions

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Berk wrote: Fri Aug 18, 2023 22:57 But this is not part of the urban road network, but a trunk road. And it’s not really about adding capacity, just ensuring the local part of the network runs smoothly, with GSJ’s.

The campaigners are basically saying they hate GSJ’s, or don’t understand that that’s not really adding mainline capacity.
Widening roads is one way to increase the capacity of roads, and so is the grade separation of junctions. The concept of induced demand applies to all roads too. I would say the A38 is more of an urban motorway/expressway than an urban road given that it runs through a fairly built-up area, but I see what you mean.
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Re: A38 Derby Junctions

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One thing that is always forgotten with the induced demand argument is that in off peak times the road will flow much better.

In other words, there are still merits to tacking road layouts to deal with unnecessary off peak congestion even if there are periods of inevitable peak congestion because of peak load.
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Re: A38 Derby Junctions

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"No you can't build anything, there's no point, people will only use it and then if your only metric is how busy it appears to be then nothing will have changed"
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Re: A38 Derby Junctions

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Berk wrote: Fri Aug 18, 2023 22:57But this is not part of the urban road network, but a trunk road. And it’s not really about adding capacity, just ensuring the local part of the network runs smoothly, with GSJ’s.
It’s a trunk road through an urban area that is intensively used for local journeys and commuting - the fact it’s maintained by NH and not the local council doesn’t change that. And grade separating the junctions is very definitely about adding capacity. That is the point - they’re congested, so extra capacity is being added to relieve the congestion. You can’t tell me with a straight face that the new flyovers and underpasses will have no greater capacity than the existing signalised roundabouts, and if you actually are saying that, then surely there’s no point in building them?
The campaigners are basically saying they hate GSJ’s, or don’t understand that that’s not really adding mainline capacity.
It very much is adding mainline capacity, which will reduce journey times on the A38 and on the roads that cross it, which will make it quicker to travel around the west side of Derby by car. It’s highly likely that new local car journeys will happen. You might not like that TAN are trying to stop it, or you might take the view that inducing extra local car journeys is OK or will be minimal and that it’s no reason to stop the project going ahead, but I don’t think there’s much mileage in making out that they’re idiots who don’t understand what the project will achieve.
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Re: A38 Derby Junctions

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Chris5156 wrote: Sat Aug 19, 2023 10:20
Berk wrote: Fri Aug 18, 2023 22:57But this is not part of the urban road network, but a trunk road. And it’s not really about adding capacity, just ensuring the local part of the network runs smoothly, with GSJ’s.
It’s a trunk road through an urban area that is intensively used for local journeys and commuting - the fact it’s maintained by NH and not the local council doesn’t change that. And grade separating the junctions is very definitely about adding capacity. That is the point - they’re congested, so extra capacity is being added to relieve the congestion. You can’t tell me with a straight face that the new flyovers and underpasses will have no greater capacity than the existing signalised roundabouts, and if you actually are saying that, then surely there’s no point in building them?
The campaigners are basically saying they hate GSJ’s, or don’t understand that that’s not really adding mainline capacity.
It very much is adding mainline capacity, which will reduce journey times on the A38 and on the roads that cross it, which will make it quicker to travel around the west side of Derby by car. It’s highly likely that new local car journeys will happen. You might not like that TAN are trying to stop it, or you might take the view that inducing extra local car journeys is OK or will be minimal and that it’s no reason to stop the project going ahead, but I don’t think there’s much mileage in making out that they’re idiots who don’t understand what the project will achieve.
I agree, but what will be interesting to see is the impact on pollution. A roundabout based route with lots of breaking and acceleration is likely to result in more pollution than a flowing route which at 50mph will generate less pollution. However, if it ends up placing more traffic on already congested urban roads then that may not be the case. The point made above though is that the A38 does form part of the strategic route between Birmingham and Sheffield and these junctions represent the only unseparated ones between the M6 Toll and M1.
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Re: A38 Derby Junctions

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AnOrdinarySABREUser wrote: Fri Aug 18, 2023 22:50
Berk wrote: Fri Aug 18, 2023 22:10 Don’t dignify them with any credit, it’s just a desperate delaying tactic. And they have to present new arguments, not rehashed old ones.

I really struggle to see why their claim that the junctions programme will increase traffic has any merit to it.
Interesting observations have been made over time on the addition of capacity to roads, in that they induce demand, as the additional capacity encourages people to drive instead of using alternative methods of travel such as public transport or cycling under the presumption that the additional capacity means that traffic will flow faster, which fills up the road again, and the cycle continues. That's not to say that adding capacity to roads can be incredibly useful, especially over the long-term, but once adding an extra lane stops having any long-term effect on congestion, then it's time to rethink the way we go about relieving roads of congestion.
To say that improvements induce demand on the route is a statement of the obvious. Traffic modelling will show that for virtually any capacity improvement. Indeed, that improves the case for the improvement, because instead of, say, 40k vehicles per day benefiting from improved journey time and safety, 50k or 60k do.

On a road like the A38 virtually none of the induced demand will be coming from public transport or cycling. Cycling has about 2% of non-motorway mileage in the UK, and probably less than that in a strategic corridor, so there is almost nothing to induce in the first place. Demand may increase for public transport, which is principally by bus. The induced demand is predominantly transfers from less suitable routes or "rat runs" as well as increased economic activity. It's a feature not a bug.

Likewise, grade separation of a dual carriageway delivers so much extra capacity that even after 10k, 20k or even 30k of induced demand, there will still be lower journey times and higher safety than there was prior to the improvement.

The point is really pretty obvious if one moves away from hypotheticals to think about actually existing improvements. No one can really imagine that the rest of the A38, or for that matter other grade separated dual carriageways like the A1, A3, A14, or A34, would deliver better journey times or safety if they had been left as S2. They would be the A303 at Stonehenge or A64 east of York on a much grander scale.
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Re: A38 Derby Junctions

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jackal wrote: Sat Aug 19, 2023 12:45 To say that improvements induce demand on the route is a statement of the obvious. Traffic modelling will show that for virtually any capacity improvement. Indeed, that improves the case for the improvement, because instead of, say, 40k vehicles per day benefiting from improved journey time and safety, 50k or 60k do.

On a road like the A38 virtually none of the induced demand will be coming from public transport or cycling. Cycling has about 2% of non-motorway mileage in the UK, and probably less than that in a strategic corridor, so there is almost nothing to induce in the first place. Demand may increase for public transport, which is principally by bus. The induced demand is predominantly transfers from less suitable routes or "rat runs" as well as increased economic activity. It's a feature not a bug.

Likewise, grade separation of a dual carriageway delivers so much extra capacity that even after 10k, 20k or even 30k of induced demand, there will still be lower journey times and higher safety than there was prior to the improvement.

The point is really pretty obvious if one moves away from hypotheticals to think about actually existing improvements. No one can really imagine that the rest of the A38, or for that matter other grade separated dual carriageways like the A1, A3, A14, or A34, would deliver better journey times or safety if they had been left as S2. They would be the A303 at Stonehenge or A64 east of York on a much grander scale.
At no point was I denying that the additional capacity will improve journey times over the long-term, nor did I ever say that we should've left important routes such as the ones you listed as single carriageway, nor do I think that the A38 Derby junctions should not be improved. I was stating that there will be an increase of traffic on the A38 over the long term because of the induced demand, which may diminish the benefits of the scheme, and that it's understandable to see why TAN are so opposed to the scheme. Whether or not that's a good argument when applied to the A38 Derby scheme is up to debate, but personally, I do think that the junctions should be improved.
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