In addition to the many errors, misrepresentations and examples of wishful thinking I identified in the ‘Intelligent Speed Adaptation’ report advised in my last email, there is another, enormous discrepancy that arguably swamps all of the others combined: The cost-benefit analysis in the report seeks to compare implementation costs for a range of ISA options with the value of accidents supposedly prevented. It is all too clear to anyone who understands numbers that it cannot fail to be very seriously compromised by the wide margins of error inevitable in the many variables, all the more so given that the predictions extend up to 60 years ahead! Who's kidding whom? At what point do suspect data, guesses, wishful thinking and adverse factors that have been ignored, fed into mathematical or computer models that necessarily depend on many assumptions of unknown validity, give answers that are so unreliable as to be worthless? How can anyone take seriously a speed limitation system that claims to be able to cut injury accidents by 29% when only 5% of injury accidents involve speed above the speed limit in the first place - or (STATS19 instructions to police) MIGHT have done? There is however one single factor which can be shown, here and now, to be blatantly false and misleading - and that is the value placed on accidents avoided. Section 6.3 on pg. 91 states that the valuations used are the DfT HEN1 figures as follows: Fatal £1,770,056 Serious £205,261 Slight £21,068. These, incidentally, are the same fatuous valuations used by some Safety Camera Partnerships to claim that their activities save more money than they cost. It was in that context, a year or two ago, that Eric Bridgstock pointed out that these figure in o way represent real costs to the state or to the economy, but are instead purely notional values allocated to pain and suffering avoided, not real money. The scale of the discrepancy is enormous - the average real cost to the State of a fatal accident is not remotely £1.77m but a few tens of thousands of pounds. There is every reason therefore to believe that on the basis of realistic valuations of accidents avoided, ISA amounts to extremely expensive nonsense - even before correcting for the other innumerable optimistic assumptions and predictions