£92m Savings a Year Probably a Lie

A lot of numbers are being thrown around to justify or not the introduction of the new 20mph speed limit in Wales, such as:

• Will save 9 lives and 98 serious injuries each year
• Will cost the economy £4.5 billion over 30 years
• Could save up to £92 million every year in NHS and other costs
• Source https://www.gov.wales/introducing-20mph-speed-limits-frequently-asked-questions#130675

This is being misinterpreted by people and the media as saving the NHS £92m year, e.g.:

It just isn't true! Drakeford and the WG are not making this claim, they word it very carefully so as not to be telling this lie but it is a bit insincere of them to intentionally pull on peoples emotional support of the NHS when the real benefit is negligible in comparison.

Where have these numbers come from? 

Research, conducted by the Transport Research Institute (TRI) at Edinburgh Napier University, in conjunction with Public Health Wales, estimated a new default 20mph speed limit on residential roads across Wales will save £92 million in the first year. 
Source: https://www.gov.wales/new-research-shows-20mph-speed-limit-could-save-wales-100-million-first-year

Based on research: https://blogs.napier.ac.uk/tri/wp-content/uploads/sites/56/2022/11/TRI-Technical-Paper-101.The-value-of-Prevention.AD_.pdf

The bottom row in this table from the Napier research is where the £92 million comes from:

Note, there is no mention in the document of these being NHS savings, just a total value of prevention per casualty.  The Senedd's own assessment in the Explanatory Memorandum to the Restricted Roads (20 mph Speed Limit) (Wales) Order 2022 document breaks that value down further, found here: https://senedd.wales/media/fo3ibze5/sub-ld15187-em-e.pdf

Jumping straight to 8.0 Conclusion, it says:

• Improved road safety resulting from a reduction in average speeds could result in a positive financial return to government from the policy over 30 years of around £25 million, due to cost savings associated with reduced emergency services and hospital treatment, with savings of ca. £58 million.

£58 million over 30 years is much less than £92 million every year, so what makes up the rest of the £92m a year or £2.76 billion over 30 years?

The actual statement by the WG is "It is estimated that the casualty prevention savings, including the reduced impact on NHS and emergency services, could be up to £92m every year."  The key words here are 'including' and 'could'.

Table 7 provides the Summary of Monetised Costs and Benefits which is where the £4.5 billion comes from:

The figures of note are:

• £57.5 million financial benefits to the WG - this will be the £58m savings from their conclusion
• £1.625 billion costs to business for increased journey times
• £4.726 billion costs to the general public for increased journey times
• £1.802 billion of other benefits for the general public

Those other benefits for the general public must be where the rest of the £92 million every year derives from but this is still around a billion short of 92*30. As noted a key phrase in the statement is 'could' - there are low, central and high values. They are summarised in Table 5 Economic Benefits:

The biggest benefit is the £1.333 billion in road safety for the general public. Appendix 5 describes the methodology for calculating this and puts a cost per casualty:

Let's combine those two matrices:

Using Central totals, it is only £1.44 million a year, £43 million over 30 years, in medical and ambulance savings, i.e. NHS. This is only 4% of the total. Best-case is still less than £2m per year.

For fatal injuries, 93% of the total value per casualty is the 'Willingness to pay' - what exactly is that?

Willingness to pay is asterisked but there is no corresponding footnote in the document to describe it. It seams, Willingness to pay is not a cost saving but an artificial figure derived by the UK Department for Transport to put a value on a persons life - basically it means how much the public are prepared to spend to prevent a death. This is all smoke and mirrors by the WG, creative accounting if you will.

See: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/995110/rrcgb-valuation-methodology.pdf

How is the Willingness to pay value calculated? It is based on research done in the 1990's where a small group of people (167 I think) where asked how much should the government be prepared to spend to save a preventable death, the average came to £1m and the DfT updates it each year based on GDP. It is completely flawed and I doubt any statistician would consider it valid.

See: https://www.bristol.ac.uk/media-library/sites/cabot---old/news/2017/What is the Value of Life.pdf

Anyway, it's the number they are using, though it should be used as a measure against which the costs are compared. If the costs to the economy are less than the willingness to pay then it may be OK legislation, otherwise, there's probably better value ways to prevent deaths - such as putting real money into the NHS. 

Note, figures across the various tables may not correspond exactly, there are many reasons for this, read the document. The data above is summarised better in A6 Extended Cost and Benefits Summary:

Removing the £1.175 billion for Willingness to pay, the true cost to the economy over 30 years is £5.658 billion, that is around £21 million per death (assuming 9*30=270 deaths) a lot more than the Willingness to pay measure.  Proportioning out the other injuries, it is still around £10 million. How many more lives could be saved if this was invested in drugs and treatments instead? It's a nonsense to say this legislation is about saving lives.

But what about the £92m? The difference between the Senedd's own data and that from Napier is just the number of casualties and a higher willingness to pay value, derived from the DfT document linked to above. 

So, drop the word could and it's a lie, in the same way that Carlsberg is probably the best lager in the World. To be fair, the the Ministers making these statements are probably just repeating the message they've been told to without having looked at the numbers themselves; these aren't the type of people I want representing me in government, though the alternative is no better!