Stonehenge - The bored tunnel option

[ManomayLR]

I presume, as with most new HQDC developments, that the traffic will be actively managed at least through the tunnel i.e. lane control, possible variable speed limits, VMS signs etc.

[jervi]

I presume, as with most new HQDC developments, that the traffic will be actively managed at least through the tunnel i.e. lane control, possible variable speed limits, VMS signs etc.

Lane control, yes and maybe a few VMS signs on either approach (and approach to the junction before tunnel) for the event that either or both tunnels are closed. However I would think its unlikely to have VSL as the road either side isn't a HQDC

[someone]

The Hindhead Tunnel has a variable speed limit notwithstanding the road on either side of it.

Admittedly, it can only vary between being 40 mph or 70 mph, but I would be shocked if any new tunnel does not have that ability to impose a lower speed limit for safety reasons.

[ManomayLR]

The Hindhead Tunnel has a variable speed limit notwithstanding the road on either side of it.

Admittedly, it can only vary between being 40 mph or 70 mph, but I would be shocked if any new tunnel does not have that ability to impose a lower speed limit for safety reasons.

Nowadays it's unlikely they'd use prism signs though, they'd probably use electronic variable speed limit/lane control signs like on smart motorways.

[Phil]

The Hindhead Tunnel has a variable speed limit notwithstanding the road on either side of it.

Admittedly, it can only vary between being 40 mph or 70 mph, but I would be shocked if any new tunnel does not have that ability to impose a lower speed limit for safety reasons.

Nowadays it's unlikely they'd use prism signs though, they'd probably use electronic variable speed limit/lane control signs like on smart motorways.

As with many other infrequently used mechanical devices, Prism signs have a tendency to stick / fail just when you need them. As such it would be foolish to perpetuate their use on road signs where electronic alternatives exist.

[jackal]

"The Planning Inspectorate has passed its recommendation on plans to build a tunnel at Stonehenge to the transport secretary but the project remains unfunded.

Grant Shapps – or his successor in any post-election cabinet reshuffle – now has three months to make a decision on the controversial scheme.

However, Highways England does not currently have a funding source for the project or the roads for the Lower Thames Crossing – another tunnel – between Kent and Essex.

Both schemes were to be privately financed until the then chancellor, Philip Hammond, placed a moratorium on PFI and PF2 schemes in the 2018 Autumn Budget.

A spokesperson for the Department for Transport told Highways that announcements on the schemes, as well as the Road Investment Strategy from April 2020, which remains unpublished, would be made ‘in due course’ – government code for the absence of a firm date."

https://www.highwaysmagazine.co.uk/No-l ... passe/5355

[Berk]

I would hope that, since Hammond is “old news”, and with Johnson desperately seeking a competitive edge/Brexit dividend, the ban on PFI-financing will quietly be reversed.

I can’t say I was too happy about that in the first place. Whilst it might deliver slightly/modestly better value for the taxpayer, there was a great risk being run of projects not being built again.

We had a great, great deal of that in the 70s, 80s and 90s. Our network has not grown as it should, as a result.

As for announcements “in due course”, that could be anything from a few years to a great months. Nothing specific should be read into that.

[JonB2028]

I thought that as part of the DCO process you had to show you had funding to build the scheme - or at least the cost of the land acquisition? (Which yes is going to be small compared with the rest of the scheme cost so I suppose they could have a whip-round for that.) The funding statement on the planning inspectorate is rather vague https://infrastructure.planninginspecto ... ANGES).pdf

[RichardA35]

If a scheme is shovel ready and you have some naive Tier 2 numpties willing to lose their shirt contractors lined up, then you would press ahead and worry about the last few schemes in the RIS when the hard questions are asked 3 years down the line.

[jackal]

I thought that as part of the DCO process you had to show you had funding to build the scheme - or at least the cost of the land acquisition? (Which yes is going to be small compared with the rest of the scheme cost so I suppose they could have a whip-round for that.) The funding statement on the planning inspectorate is rather vague https://infrastructure.planninginspecto ... ANGES).pdf

Thanks for that, which confirms the previously proposed PF2 model as 'DBFM CO' raising and paying the £1.4bn construction cost, and Highways England paying them a Unitary Charge for up to 30 years to cover this.

As I've said before, the current furore is a mountain out of a molehill. The government were always paying the construction cost+financing cost, just through the intermediaries of DBFM CO and HE. They can achieve much the same by borrowing the money themselves, which should if anything lower the cost to public finances because they can borrow at a lower rate than DBFM CO. I expect this will be announced soon enough.

[Jim606]

The Hindhead Tunnel has a variable speed limit notwithstanding the road on either side of it. Admittedly, it can only vary between being 40 mph or 70 mph, but I would be shocked if any new tunnel does not have that ability to impose a lower speed limit for safety reasons.

Your right, I guess the Stonehenge tunnel will be the same? However, it is for good reason, as I don't think there has ever been a fatal accident in the Hindhead tunnels since there opening which is a good thing. What happens at Hindhead when they close one or both of the tunnels? Do they have a system for bi-directional traffic in one tunnel or do they closed both at the same time?

[someone]

What happens at Hindhead when they close one or both of the tunnels? Do they have a system for bi-directional traffic in one tunnel or do they closed both at the same time?

Yes, they operate either tunnel in both directions whenever required.

The area between the carriageways immediately before and after the tunnels are paved for traffic to crossover, with movable central reservation barriers, and obviously there are lane control signs within the tunnels.

Such a simple system it would be foolish to not have it.

[Jim606]

Yes, they operate either tunnel in both directions whenever required. The area between the carriageways immediately before and after the tunnels are paved for traffic to crossover, with movable central reservation barriers, and obviously there are lane control signs within the tunnels. Such a simple system it would be foolish to not have it.

Thanks for that. Stonehenge will no doubt be the same.

[Chris5156]

Lane control, yes and maybe a few VMS signs on either approach (and approach to the junction before tunnel) for the event that either or both tunnels are closed. However I would think its unlikely to have VSL as the road either side isn't a HQDC

I would expect the Stonehenge Tunnel and Winterbourne Stoke Bypass to be built to HE's expressway standard, with VSL capability.

I'm intrigued about why you think the road either side is not HQDC. The proposed road will link with about 4 miles of comprehensively grade-separated dual carriageway, built to modern standards, at the western end and 27 miles of dual carriageway which is almost completely grade separated at the eastern end, making a continuous expressway of about 38 miles when finished.

[SouthWest Philip]

I'm intrigued about why you think the road either side is not HQDC. The proposed road will link with about 4 miles of comprehensively grade-separated dual carriageway, built to modern standards, at the western end and 27 miles of dual carriageway which is almost completely grade separated at the eastern end, making a continuous expressway of about 38 miles when finished.

I suspect what jervi is alluding to is the fact that the A303 immediately to the east of Amesbury is a bit ropey by current standards particularly with regards to still having several gaps in the central reservation with at-grade crossings. There is also a fair gradient climbing eastbound. As this section was an online upgrade, there is also no parallel local access road. Would take a bit of work to bring up to Expressway standard.

[Berk]

That’s not the case though. If you read the full DCO application documents (or the ones on HE’s website), they are certainly planning to close some accesses around Solstice Park.

[jervi]

I'm intrigued about why you think the road either side is not HQDC. The proposed road will link with about 4 miles of comprehensively grade-separated dual carriageway, built to modern standards, at the western end and 27 miles of dual carriageway which is almost completely grade separated at the eastern end, making a continuous expressway of about 38 miles when finished.

So it is true that the majority of junctions along the A303 either side are GSJs, however I wouldn't say they are anywhere near motorway-standard. And it isn't clear what "expressway" DMRB standards requires. Do Junctions to be the standard for 120MPH DC or Motorway, or maybe a relaxed motorway standard?
Also there are a large amount of gaps, and many local roads having LILO access.
I wouldn't expect VSLs on such a short section of road, the most I'd expect is MS4s which will give advisatory limits, which could also double up of giving messages of tunnel closures. Its like the A27 Arundel Bypass, it is expected to be 7km, however I doubt they would install VSLs as part of the "expressway" idea since it will be of no benefit until a larger stretch of the road also gains the technology and there is a justified reason to install it. But again, I'd expect MS4s to be installed since they benefit the network by giving warnings of closures (and accidents) and can give advisory limits.

[Herned]

So it is true that the majority of junctions along the A303 either side are GSJs, however I wouldn't say they are anywhere near motorway-standard. And it isn't clear what "expressway" DMRB standards requires. Do Junctions to be the standard for 120MPH DC or Motorway, or maybe a relaxed motorway standard?
Also there are a large amount of gaps, and many local roads having LILO access.

There are only two gaps between Amesbury and the M3, both on the section immediately east of Solstice services. Everything else has been closed or was built to modern standards. All the junctions with any significant traffic are motorway standard, the Andover bypass junctions are much higher quality than would be built on a new motorway today! It's true that there are some local accesses which a motorway wouldn't have, but they serve isolated properties or businesses so the BCR of doing anything about them is probably non-existent

[Chris5156]

So it is true that the majority of junctions along the A303 either side are GSJs, however I wouldn't say they are anywhere near motorway-standard. And it isn't clear what "expressway" DMRB standards requires. Do Junctions to be the standard for 120MPH DC or Motorway, or maybe a relaxed motorway standard?

HE's "expressway" standard isn't in DMRB. Their requirements for expressway status are:
- grade separated junctions with left-hand exit and entry sliproads; occasional roundabouts are also permitted
- 70mph limit where possible
- provision for non-motorised users off the main roadway, and non-motorised users banned from using the road
- Traffic Officer service
- emergency lay-bys and refuge areas
- electronic message signs

The aim appears to be to progressively upgrade existing high quality dual carriageways to meet this standard, as funding is available and improvement work is done. For the length of A303 in question:
- if, between the M3 and Amesbury, there are just two central reserve gaps then we are already very close to meeting the requirement for junctions
- the road already operates at 70mph
- removal of NMUs might be tricky, it will depend what's already available for NMUs section by section and what has to be provided
- Traffic Officer service can be done as and when HE decide to recruit staff and buy some Range Rovers; for all I know it already has this service
- plenty of lay-bys already; if required these could be adapted or restricted for emergencies only
- electronic signs would require a communications upgrade

So the A303 isn't expressway standard yet, but it's further along the pathway to being a full-blown expressway than many of Highways England's other rural A-road dual carriageways. Given its current state, and the DfT's stated policy aim of creating an "expressway to the south west", it would astound me if the Stonehenge scheme wasn't full expressway standard, or something very close that could easily and cheaply be brought up to standard later.

[jervi]

So the A303 isn't expressway standard yet, but it's further along the pathway to being a full-blown expressway than many of Highways England's other rural A-road dual carriageways. Given its current state, and the DfT's stated policy aim of creating an "expressway to the south west", it would astound me if the Stonehenge scheme wasn't full expressway standard, or something very close that could easily and cheaply be brought up to standard later.

Totally agree with you, It would be built to expressway standards (minus AMIs and VSL). I'm saying it is unlikely to be built with AMIs & VSL already in place, however would be designed in such a way that installation of additional gantries to hold AMIs could take place with near zero works to the road and embankments. Then when funding allows the rest of the A303 to be upgraded to an expressway, then ganties and AMIs could be installed on this section. Also MS4's would be installed as part of this scheme, as it would be a benefit right away notifying drivers of current and future closures as well as incidents on the SRN nearby and advisory speed limits.