Fit To Drive
Once more the media appear to be wading in to the campaign to lower the legal driving limit for blood alcohol to 0.05%. Strangely, they quote the recent spate of road traffic fatalities as if this somehow bolsters their argument. This is simply lazy journalism. There is plenty of evidence that lowering the legal Blood Alcohol Concentration (BAC) reduces accident rates, injuries and fatalities in an almost linear fashion (at least below about 0.1%). Here is a link to the very latest meta-analysis. Click on the Table/Figures tab and look at the thumbnail of figure 5 (you will have to purchase the article if you want the enlarged figure – but you can clearly see the trend).
The problem is actually not the amount of alcohol in your blood stream, but the degree of impairment when you drive.
”The point is that the effect of alcohol is fairly linear. In fact, there is evidence that the largest deterioration in performance occurs at quite low levels of intoxication (0.01-0.03%) but this does not initially translate into increased accidents (One assumes that the deterioration – although large proportionately – is still not enough to cause a noticeable increase in risk). Because the increase in risk is quite linear, it follows that the setting of a new BAC at 0.05% is entirely arbitrary. Indeed, the Japanese have shown that dropping the limit from 0.05% 0.03% produces a significant drop in accident and fatality statistics. It will therefore not be long after a drop to 0.05% that people (particularly ED doctors who bear the brunt of traffic accident injuries) will be calling for a further drop. It is not logical to go to all this trouble to fix the legal BAC at yet another arbitrary limit. There is no “safe” level of drink driving.
Worse still, the problem is actually not the amount of alcohol in your blood stream, but the degree of impairment when you drive. While there is statistical correlation between accidents and alcohol, alcohol is by no means the only reason why a person may be driving-impaired. Cannabis intake markedly increases driving impairment, as do most of the sedative and psychotrophic drugs. Some normally benign drugs increase drowsiness and decrease driving ability in the presence of a small amount of alcohol. Even individuals with the same levels of blood alcohol will have differing levels of impairment, depending on their ability to compensate for alcohol intoxication (but note that the reaction time of said individuals is still reduced to the same extent – they are just better at compensating for it).
The point here is that an arbitrary limit for alcohol intoxication is inadequate for determining whether someone is safe to drive. Even at a zero level of alcohol, other drugs may make the driver decidedly dodgy behind a wheel. It is also doubtful that any movement of the BAC limit, even to zero, will make any difference to the kind of people who get behind the wheel of a car with a BAC 0f 0.18%. As I have posted before, the only solution to that kind of fool is to change the current drink driving laws from a minor punishment to a draconian deterrent.
MacDoctor has a somewhat radical suggestion. Let us scrap the legal limit for alcohol altogether. Instead, we should substitute a legal requirement to be “fit to drive”. Should you be stopped at a police checkpoint and the cop has any reason to believe you may be impaired in your ability to drive (including checking your breath alcohol), he can insist that you take a “fit to drive” test. Failure (to take or pass the test) will get you arrested. The test could be administered using driving simulators in the back of a police van (basic tests administered by cops – such as walking a straight line – are simply too imprecise).
The advantage of a “fit to drive” test is that it catches all the impaired drivers, not just the ones impaired by excessive alcohol. It also avoids the problem of the margin where the person with the BAC of 0.052% is carted off to jail, despite being only mildly impaired, and the person with the BAC of 0.048% is let go, despite being high on cannabis and a liability on the road. It also standardises the drug tests that the new drug driving laws propose – making them considerably more objective. It will also prevent people from using portable breathalysers so that they can drink “to the limit” regardless of how capable they are of driving.
Some capital investment on the machines to test people will have to be made. I suspect you will find that the investment will be recuperated in reduced hospitalisations alone, let along the enormous ACC rehabilitation bill that drink-and-drug-driving causes each year. All that it requires is the political will to step away from conventional thinking and try an new approach.
Are you reading this, Mr. Joyce?
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Apr 10 10 9:02 pm
I agree with what you are saying to a large degree. Although the drug driving laws were tightened up in NZ at the end of last year, the impairment tests that drivers are now required to do have a subjective interpretation – being dependent upon the experience of the officer concerned (not very, in most cases at this stage in proceedings) and how lenient or strict they want to be in interpretation. The blood analysis has to be taken in to account but that won’t stop someone who’s impaired from taking the wheel. The problem is of course that most people don’t realise they’re impaired or do realise but are too far past caring to take it seriously.
Even a ‘testing machine’ in the back of a police van would have its problems because these are people we’re dealing with. Perhaps Sweden will be the first to start development of such equipment, particularly as they have been leaders in drink driving research (largely as the result of Wayne Jones living there, who was involved with the development of one of the world’s top breath testing instruments when he still lived in Wales).
Although less alcohol and drug driving would mean less case work for me, I’d be happy to find other areas of work to keep me gainfully employed if it meant less pointless deaths on the road.
Apr 10 10 11:30 pm
Note that the machinery for testing road performance is already available and requires little development.
Apr 10 10 9:14 pm
It’s a good thought, but it’s hard to imagine a “fit to drive” test that wouldn’t be failed by a significant proportion of NZ drivers even when completely sober. On the other hand, maybe that’s not a drawback…
Apr 10 10 11:35 pm
Not really, PM. The test would only test reaction timing and basic decision making. It would not be a skills test per se.
Apr 13 10 8:59 pm
Flicker fusion comes to mind as a simple test that correlates with alcohol levels, but that is the start of a circular argument about safe driving…
As I recall, the early work on this was with bus drivers (ie professional, experienced drivers). The studies asked them to look at a couple of cones, say if they could drive their bus between them, then do it. The key finding was the impairment of judgement. In that as alcohol intake increased the drivers not only became more likely to hit the cones when there was room but also to judge that they could drive through a gap narrower than the bus.
A similar gap-judging test might not be too hard to administer at the roadside.
Obliquely related – I know that one beer is enough to significantly impair my ability to play musical instruments (not great to start with) which links to your comments about impairment at low levels.
Apr 10 10 9:55 pm
MacDoctor, I think the problem with your theory is the same as for young drivers. You can test a person’s reaction speed and such on a simulator but that does not tell how they will react if someone cuts in on them. A mature driver who has had nothing to drink will just move back to a safe distance. Than same driver may have their reaction spend slowed a little but will behave in a similar manner with a two or three glasses of wine.
A younger driver is more likely to retaliate sober and much more so if then have been drinking.
It would appear the main research this government has done is to follow their internal polling to see if they will gain more votes than they will lose.
I do not trust their so called research. The government should make a genuine effort to address the issue of recidivists very drunk drivers who continue to driver without a license before they make criminals of a couple who wish to share a bottle of wine over a meal.
Apr 10 10 11:47 pm
Chuck. I am specifically thinking of reaction time and decision making. I freely concede that someone may be perfectly sober and have good reaction times but be a worse driver than someone with slow reaction times, purely due to their driving skills. I am also aware that a 20-year-old with a BAC of 0.05% may have better reaction times than an 80-year-old.
In the first case, I don’t think this is about making everyone a good driver. It is only about not letting people drive when they are impaired. In the second case, if a sober 80-year-old fails the “fit to Drive” test, I question whether s/he should be allowed to drive.
Apr 12 10 8:35 am
This would require people to take responsibility for asessing themselves rather than adhering to a set limit – it’s a radical concept but if it could work it ought to make the roads safer.
.-= Homepaddock´s last blog ..How much is too much? =-.
Apr 12 10 3:45 pm
Agree with what you say except for particularly ED doctors who bear the brunt of traffic accident injuries
um how about the vollies in the Fire Service and ambo’s? I have spent plenty of time cutting out people (live and deceased) and cleaning them up before they hit the emergency room.
Apr 12 10 8:58 pm
Granted the fire service and ambo’s bear the initial brunt of the mess, but my point is not who does the most, but who is the noisiest. In general, ED doctors are the one’s calling the loudest for a drop in the legal BAC – second only to the police.