Tuesday 24 January 2017

Notes on the Stonehenge Tunnel Proposal

It is important to acknowledge that there are many good and valid reasons why the A303 needs to be improved as it passes Stonehenge. If the monument wasn’t there it would be a trivial Highway engineering problem. We must therefore also acknowledge that the taxpayer is expected to pay something in the order of £1.5 billion in additional costs to protect the World Heritage Site. The benefits to the setting of Stonehenge and associated monuments are largely obvious and need no extensive recital here. These notes only cover the broadest outline of the plan and not minor details.

Highways England have commendably included a mass of technical documents on their consultation page about the Stonehenge Tunnel (https://highwaysengland.citizenspace.com/cip/a303-stonehenge/ ). They include the technical reports and particularly in TAR appendix G and H they score their proposals against the various aims and policies of the stakeholders.
They are holding a series of exhibitions over the next few weeks where the details can be examined and experts are on hand to answer questions. I would recommend visiting one of these.

Originally they narrowed down the options to the tunnel or a southerly non-tunnelled route that would take the A303 outside of the WHS completely. The latter is no longer apparently an option.
They are two options up for discussion. They differ as to whether they take a northerly or southerly route around Winterbourne Stoke. By their criteria there is little to choose between the two options and having studied them both there is no obvious reason relating to Winterbourne Stoke which one to prefer.


The route within the WHS can be split into the eastern and western end for consideration. It can be presumed that, unless another Wilsford Shaft is on the route, the tunnel itself has no possible adverse effect on the area’s archaeology. There is a question as to whether it might change the hydrology and aquifer which might be detrimental to the springs at Blick Mead but that is a question that needs relevant expertise to answer and I am satisfied that Highways England are fully aware of it and will take appropriate measures.

The eastern end of the route involves a new flyover at Countess Roundabout, mainly utilising the present A303 until it reaches a new portal just to the east of where the Avenue crosses the A303, out of sight of Stonehenge.

There is a small area of virgin land that will lost to the portal which is close to Mesolithic finds and the scheme passes close to Blick Mead. The balance of landscape and archaeological loss and gain is so narrow that the cost of moving the portal to the east of the WHS could not be justified to me.

Others with more knowledge and involvement in that area disagree. There certainly is a case for the flyover at the Countess Roundabout running north-south rather than east-west to keep the height of the A303 the same.

The western portal is designed to be hidden from Stonehenge by the small wood at Normanton Gorse and the twenty foot high ridge the wood is on.

The western portal and the new road are planned to be within the vicinity of the Mid Winter Solstice Sunset (MWSS) alignment of Stonehenge. The precise location is still under development, but is expected to be very close to the plans made available for consultation



Detail from plan with MWSS alignment added in red.

Attention has mainly been given so far to the danger that the road will spoil the dark sky and the solstice sunset. Highways England’s Volume 1 TAR red section 8.6 details the assumptions about carriageway and portal lighting, and that until a detailed assessment is done the assumption is that there will be none. My opinion is that even if there is no lighting planned there is a real danger that it will be added, as has happened on so many roads, at a later date for safety reasons. There will, especially with the southern route, shown in orange, also be vehicle lights impacting the night sky.

But the danger of spoiling the night sky is only a part of the problem.

Siting the portal and road within this the most important astronomical alignment of Stonehenge is contrary to the UNESCO Statement of Outstanding Universal Value (see below) and UNESCO’s Astronomy and World Heritage Initiative recommendation with regard to the alignments that: “Assuming that these were once largely clear in the Neolithic and Bronze Ages, it is important to try and ensure that the sightlines are as clear as possible today. All plans should ensure that no further planting or development takes place along them.”

In addition the Stonehenge and Avebury World Heritage Site Management Plan 2015 (http://www.stonehengeandaveburywhs.org/assets/Stonehenge-and-Avebury-WHS-Management-Plan-2015.pdf) lays out various policies including:
Policy 3c – Maintain and enhance the setting of monuments and sites in the landscape and their interrelationships and astronomical alignments with particular attention given to achieving an appropriate landscape setting for the monuments and the WHS itself.

It can be seen that by ignoring the astronomical alignments and sightlines in their assessment the plan fails both the UNESCO and the local policies.
I believe that this part of the plan is unacceptable for these reasons and there is still time to influence the design to be changed to a more acceptable solution. As Highways England say in their proposal document; “The precise location and design of the portals at either end of the tunnel is something we will be developing in consultation with heritage stakeholders and to take account of additional survey work as it becomes available.”


Appendix:
Extracts from UNESCOs Astronomy and World Heritage Initiative
One of the most important features of Stonehenge one that has been recognised since the 18th century when it was noted by the antiquarian William Stukeley is that its principal axis of symmetry is aligned upon winter solstice (midwinter) sunset in one direction and summer solstice (midsummer) sunrise in the other...

Stonehenge WHP can and should be seen within a regional context of sites in the Neolithic and Bronze Age in north-west Europe that have astronomical alignments. These include monuments such as the Newgrange passage tomb, part of the Br
ú na BóinneArchaeological Ensemble of the Bend of the Boyne WHP, and various stone circles and monuments. All seem to have had some sort of funerary or ceremonial function, although astronomical practices in domestic contexts are also noted on occasion.

The monuments of the Stonehenge WHP provide the earliest evidence in Britain or Ireland of a consistent local practice of aligning monuments with some precision upon sunrise or sunset around the solstices. This is in contrast, for example, to the solstitial orientation of Newgrange, a
one-off alignment among the Boyne Valley tombs; to the very broad pattern of orientation clustered around the intercardinal directions observed among Neolithic tombs and houses in the Orkney Islands; and to evidence that Early Neolithic long barrows in the Salisbury Plain area, in the vicinity of Stonehengewhich preceded the construction of the Stonehenge stone circle by about a millenniumfollowed a broad pattern of orientation within the sun-rising/sun-climbing arcs, between north-east and south...

In prehistory, one or more observers would probably have stood at an appropriate point and viewed the sun or moon appearing or disappearing behind a distant horizon at specific times of the year. Thus, clear and unobstructed sightlines and horizons are important to aid our understanding of how these monuments functioned...



There is a growing consensus that the midwinter sightline was more important than the midsummer one. Today the integrity of this sightline, and its intermediate ridge lines and final horizon, is marred. Looking out from Stonehenge, the first problem is the A303 (0.5 km), which runs relatively close to the monument, and presents a considerable visual and noise intrusion to this alignment. Moving further south-west, the round barrow known as the Sun Barrow
which is on the alignment and on the Normanton Down ridge lineis intact (0.9 km), but the sightline then quickly runs into the plantation known as Normanton Gorse (1.1 km), which obscures it. Still further south-west is another plantation known as The Diamond (2.2 km), before the alignment continues towards the place that would form the visible horizon from Stonehenge in the absence of intervening vegetation, at Oatlands Hill to the west of the A360 road (and outside the WHP) (4.4 km). This horizon is also obscured by yet another plantation, at The Park. The sightline probably ends at the site of a much later Iron-Age/Romano-British settlement. It is difficult to determine the exact place because the various obstructions mean that we must rely upon computer modelling.

The Stonehenge Avenue looking south-west (midwinter sunset) shares the same alignment, and the same issues apply regarding its integrity. On the initial approach towards Stonehenge along the Avenue from the
elbow at Stonehenge Bottom, Stonehenge itself forms the horizon; the more distant landscape only appears during the final stages of the approach.


A retrospective Statement of Outstanding Universal Value (SOUV) was prepared for the Property by the State Party in 2011 and has been approved by UNESCO. The relevant parts of that SOUV in relation to astronomy are quoted here:

Statement of Significance

The Stonehenge, Avebury and Associated Sites WHP is internationally important for its complexes of outstanding prehistoric monuments


They provide an insight into the mortuary and ceremonial practices of the period, and are evidence of prehistoric technology, architecture and astronomy


The complexes of monuments at Stonehenge and Avebury provide an exceptional insight into the funerary and ceremonial practices in Britain in the Neolithic and Bronze Age. Together with their settings and associated sites, they form landscapes without parallel.

The design, position and inter-relationship of the monuments and sites are evidence of a wealthy and highly organised prehistoric society able to impose its concepts on the environment. An outstanding example is the alignment of the Stonehenge Avenue (probably a processional route) and Stonehenge stone circle on the axis of the midsummer sunrise and midwinter sunset, indicating their ceremonial and astronomical character



Assuming that these were once largely clear in the Neolithic and Bronze Ages, it is important to try and ensure that the sightlines are as clear as possible today.
 All plans should ensure that no further planting or development takes place along them.

1 comment:

  1. 'It is important to acknowledge that there are many good and valid reasons why the A303 needs to be improved as it passes Stonehenge. If the monument wasn’t there it would be a trivial Highway engineering problem. We must therefore also acknowledge that the taxpayer is expected to pay something in the order of £1.5 billion in additional costs to protect the World Heritage Site.'

    £1.5 billion is an awful lot of money especially when there is no guarantee costs won't rise. You're right in saying that a solution needs to be found to the A303, but the provision of a new bridleway cum local access road to the south of the A303 (Stonehenge Bottom to Longbarrow Crossroads) could help separate more localised traffic from the main flow. It would also have the advantage of being very cost effective and could easily be taken away in future years, if deemed unsuitable. Once the tunnel is built we are stuck with it forever.

    'Others with more knowledge and involvement in that area disagree. There certainly is a case for the flyover at the Countess Roundabout running north-south rather than east-west to keep the height of the A303 the same.'

    Yes agreed, at Countess East the new bridge could be built to be north to south with the main carriageway staying at ground level. This would reduce the 'bulk' of the new grade separated junction. Whilst they are at they could build a new Park & Ride at Solstice Park to reduce the number of vehicles traversing the WHS. Shuttle buses could then drop visitor off at Stonehenge Bottom, Access to the stones would then be by a subway under the existing A303 embankment and a new path along the line of old A344 (permissive route) or via the Avenue in the summer months. Visitors would then exit via the VC and gift shop and get the shuttle back to Solstice Park.

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