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Stonehenge and the billion pound stated preference survey

26 April 2019

It’s not new, of course, for transport schemes to take account of wider effects. Health, quality of life, the damage or destruction of buildings, air quality and climate change are increasingly recognised, quite rightly in my view. This is sometimes done by including hypothetical money values, and where such values are soundly based they can be helpful. But anybody who does this sort of work knows how very sensitive the answers are to exactly how such questions are worded, and who is asked, and how the information is analysed. 

A road scheme near Stonehenge, promoted by Highways England and critiqued by the Stonehenge Alliance, may radically change the scale and direction of such methods. 

The scheme includes a two-mile twin bore tunnel. Its first listed objective is to “create a high quality reliable route between the South East and the South West that meets the future needs of traffic”, and the third is to “help conserve and enhance the World Heritage Site and make it easier to reach and explore”. 

There are some very odd features of the appraisal. The first odd thing is that the ‘Business Case’ gives virtually no regard to all the important work that the DfT has done on forecasting and scenarios in the last four years. Readers of Local Transport Today (14 Dec 18) may remember an important speech by Patricia Hayes, the DfT’s director of roads, in which she said that “more emphasis will be given to appraising schemes against different scenario tests, reflecting the DfT’s move to scenario forecasts for road traffic”. Sadly, such results are not included. The old approach has been used, with a core or ‘most probable’ forecast and a narrow range of sensitivity tests, which hasn’t been DfT practice since 2015. The result is an assumption of sustained traffic increases into the future, higher than the flat trends in the area since 2002 and with no recognition of recent falls in trip rates. Nor, conversely, is there any consideration of much higher traffic growth rates if low or zero energy costs or autonomous vehicles provide universal access to cheap car travel.  

So if this was a normal scheme, my hypothesis is that “meeting the future needs of traffic” would probably fail in both contexts, overestimating congestion benefits against a sensible low growth scenario such as the DfT has included in the national forecasts, and unable to reduce congestion with a high growth scenario. 

But in a way that doesn’t matter, because if we assume that all the forecasts and methods are perfectly accurate, there is a robust conclusion that the scheme makes a net loss, in cost-benefit terms, of over £800m. In transport terms, the scheme is not remotely close to demonstrating good value for money. 

The second odd thing is not that a ‘heritage value’ has been added to the conventional effects, but that it is so huge. The suggestion is that the tunnel, by removing traffic from the vicinity of Stonehenge, has a ‘heritage value’ of £1.3bn, discounted to just under a billion pounds at 2010 prices, which is three times greater than all the other claimed benefits of “meeting the future needs of traffic”. As far as I know this is the first case where the heritage benefits, as reported, are so overwhelmingly greater than the traditional costs and benefits.  

The third odd thing, ironically, is that it’s still not enough. Even with a billion pounds of heritage benefits, and the small transport benefits, the scheme still only just has a positive present value, with a benefit to cost ratio of 1.08 to 1.14, not nearly sufficient to be called good value for money. Maybe the scheme will get the go-ahead and maybe it won’t, but if it does it won’t be because all that technical work has shown it to be worthwhile. A go-ahead would have to depend on a judgment that both the transport and the heritage calculations are wrong.

And the fourth odd thing is that all that billion pounds worth of heritage value has been produced by one small piece of technical work, in a relatively short Appendix to an Appendix towards the end of the fifth volume of document 7.5. It is the single most influential report in the appraisal. It reports a survey of visitors to Stonehenge, and of the general public, asking them what increased amount of tax they would be prepared to pay, for three years, choosing from set values on a card, to ‘remove the road’ in an unspecific way that does not seem to correspond with the actual scheme. There is no countervailing estimate for any heritage damage done by tunnel entrances and highway cuttings. 

This document, highly technical and academic in style, was written by a consultancy called Simetrica, in early 2017. It carries a caveat: “The Arup Atkins Joint venture assumes no responsibility to any other party [i.e. other than the Highways Agency] in respect of, arising out of or in connection with this document and/or its content.” There is an empty space for signing it off by Highways England, which hasn’t been done. Although peer review from two referees is mentioned, their reports are not included, and Highways England’s own assurance of the data was apparently not completed.

There is a list of 65 published papers cited, but none of them is included in the documents in support (which strictly should have been done according to the examination rules). Only two of them seem to relate to roads, one from the Czech Republic, and the other – co-written by one of the authors of the Simetrica report – a 1998 study of the heritage value of removing roads from Stonehenge, using a similar method, which estimated a very much lower value of £150m for the heritage value. The difference is unresolved. Every paragraph of the report has a critically important judgment, assertion or assumption. It surely deserved the type of transparency and scrutiny that the DfT nowadays accords to technical methods – consultations, scrutiny, independent assessment, written and spoken discussions. It was written over two years ago: there was plenty of time to have enabled at least the DfT’s network of experts and consultants to have understood and assessed the work. This is an important piece of work. It’s simply not fair, I think, for such controversial, profound, pivotal, but highly technical work, to be treated in such a low key way.  

I’m in two minds about the implications of including these results in transport appraisals. The problems – as ever – are that inclusion can provide a spurious air of precision, and encourage completely unlike ‘prices’ to be added together. Stonehenge itself is of course unique, but there are very many other things that people are not being offered which they might equally legitimately be asked to express their values on, in the same hypothetical way. How about a different way of spending money on Stonehenge – a billion pounds would provide some superb archaeology, and amazing virtual reality experiences? And why not restoring cuts to local bus services, or more for nurses, or children with special needs? That would produce a very interesting change to the way in which tax levels and spending are set.    

Or global climate change. 

The fifth odd thing about the appraisal is that there are already other environmental elements included in the appraisal, with no particular attention: the extra road capacity is estimated to induce quite a lot of extra traffic, with consequent effects on air quality and on carbon dioxide emissions. They are also given a price, but not using this survey method. There are over £900m of benefits for moving the traffic further from Stonehenge, but £90m of loss for the additional CO2 this would generate. 

Are we quite, quite sure that this is right? I just can’t help thinking what sort of figures would be produced by an identical type of survey of what people would hypothetically be prepared to pay in extra tax to meet the environmental policies we are committed to, or what compensation they would consider acceptable for failing to do so. Let’s do it! 

Phil Goodwin is emeritus professor of transport policy at both the Centre for Transport and Society, University of the West of England, Bristol, and University College London. Email: philinelh@yahoo.com

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