Two drinks max

The Herald on Sunday has launched its drink driving campaign. It is primarily focused on persuading individual NZers to pledge two drinks max, with the objective of a law change less prominent.

I have no problems with people pledging not to drive after a certain amount of alcohol. I would note that a flat limit which takes no account of time period seems rather simplistic. Sometimes I may go to the Backbencher at 6 pm and stay on for Backbenches, and after that head into town until 2 am. Over those eight hours I might have four standard drinks (and a lot of non alcohol drinks and food), but would be well under 0.05 BAC.

I do take issue with one part of their story:

Science, too, is on our side. Last year, 129 people died on New Zealand roads as a result of alcohol-related crashes. Many – the transport ministry projects 150-33 lives a year – could be saved if the drink-drive limit was lowered from 80mg to 50mg.

I presume the 150 is a type, and it is meant to be 15-33. I point out again what the official stats tell us:

The only data we have at the moment is the stats on blood alcohol level amongst deceased drivers. They show over the last five years that 18 deceased drivers had a BAC between 0.05 and 0.08.

But that number is misleading as it includes those aged under 20, for whom it is already illegal to drive with a BAC over 0.03. That knocks it down to 12. That is 12 out of 1,168 deceased drivers or 1% of the total.

12 over five years is 2.4 a year. The number of dead drivers is over half the number of total dead on the roads, so I would say 4 – 5 people a year would be “saved” by a law change – that is if assuming those drivers would not have driven if the law changed.

As I said yesterday, I am willing to be persuaded that a change is desirable – but to do that we need to collect better data and not have nonsense claims about 33 lives a year, hen only 1.4 deceased drivers a year test between 0.05 and 0.08.

While I think the two drink max limit is a bit simplistic, I understand the need for simplisticity in mass media campaigns. If the HoS campaign helps reduce the road toll voluntarily – then good on them. I suspect though that it will mainly affect the low risk drivers, and have little impact on the recividist drunk drivers who cause so much of the damage.

Actually, that would be an interesting stat – and one I am do not know of. How many of those drivers who die in fatal car crashes have a conviction for driving over the limit?