Correlation: DUI arrests and Road Safety.

Is there any good research or statistics out there that actually shows where DUI laws and lower BAL limits are actually making the roads safer? Whenever local departments talk about beefing up their DUI traffic enforcement, the only statistics I can find are that there are more DUI Arrests. This is always followed by a statement about how the streets are so much SAFER. Is there anything proving this? Besides popular opinion, that is? Any numbers that support such claims?
The only statistics I can find when states crack down on DUIs is more DUI Arrests. I haven’t seen anything that shows less accidents, or less fatalities or anything.
Anyone know where there is some numerical evidence?
Is stricter DUI legislation and enforcement a political heart warmer, or is it actually accomplishing anything?

This graph from the RTA (Roads & Traffic Authority) of NSW (New South Wales) shows road accident deaths since 1934. The significant drop in the mid 1980s is attributed to the introduction of RBT (Random Breath Testing) in NSW. The RTA claims that RBT achieved an immediate 22% reduction in total fatal crashes.

Couldn’t that drop also be attributed to safer cars? Have the number of actual accidents (and not just fatalities) dropped as rapidly?
Also, another statistic on that site mentions that 20% fatalities every year are caused by alcohol. But it doesn’t show where the percentage of accident fatalities every year caused by alcohol have been decreasing.

If the statistics showed that in or about 1980, the PERCENTAGE of accident fatalities caused by alcohol has decreased, then that would be better proof. But if the percentage of fatalities has always been around 20 percent or so, then a total reduction in traffic accident fatalities would not be due to RBT.

Thank you for your cite. I’m going to continue looking for solid evidence that can’t be explained by other factors though. I need some concrete evidence.

Do all areas around you have similar laws as NSW? Are the areas which did not implement RBT not showing such a dramatic drop in fatalities?

Mods, on second thought, this question could quickly become a Great Debate. Where do you think it belongs?

Sorry Bear. I don’t know all of the answers. I’m just pointing out that governments (and in particular, the NSW state government) claim that RBT has significantly reduced the road toll. I’m sure it’s not the only factor that has had an effect. Safer cars would be another obvious one.

All Australian states have RBT laws. And I’m pretty sure that they’ve all experienced similar dramatic reductions in the road toll since the introduction of RBT.

Not at all. I don’t expect you to. I’m just throwing those questions out there for everyonel.

All the governments seem to be doing that. And I got to thinking about it and realized that I haven’t really seen any proof to back that up. For instance, your cite doesn’t even say that there are fewer “accidents” every year. Just that fatalities are down.

It is very possible that:

1)Overall Vehicular Accidents are on the rise and have been since 1980.

2)The percentage of accident fatalities caused by alcohol has increased from 10% in 1980 to the current 20%.

3)The percentage of nonfatal crashes caused by alcohol are steadily increasing.
But,

4)The overall traffic fatalities have been decreasing since 1980

All of thse could be TRUE and we’d still have the same numbers on that website. So that graph can’t really prove the governments position that RBT or lower BALs is having such an effect.

You have touched on a basic law of statistics:

Correlation does not equal causation.

Were there any new seat belt laws passed near the same time? Introduction of airbag systems?

I don’t have a cite for this but I am suspicious of the stats MADD uses to justify arguing in favor of ever harsher DUI penalties. I think they consider it to be an alcohol related accident when a beer delivery truck hits a pedestrian. Having said that, I don’t have any data to justify my position.

The wearing of seat belts was made compulsory in NSW in 1971. I’m not sure about airbags. They may be compulsory now in all newly manufactured cars, but lots of older cars are still on the road and wouldn’t have them.