[Flash Walken]

From a post back in 2008

DOPE DRIVERS SAFE: STUDY

A study funded by the British government has concluded that regular marijuana users drive more safely under the influence of cannabis.

The study of 15 users, conducted by Britain's Transport Research Laboratory, found that the mellowing effects of marijuana made drivers more cautious and less likely to drive dangerously. While marijuana did effect drivers, it was less dangerous than driving while fatigued or drunk.

Regular cannabis users were supplied with "Grade A" marijuana from the U.S. for the study. They took four weeks of tests on driving simulators to gauge their reaction time.

"MARIJUANA AND ACTUAL DRIVING PERFORMANCE":

U.S. Department of Transportation,
National Highway Traffic Safety Administration
(DOT HS 808 078), Final Report, November 1993:

"This program of research has shown that marijuana, when taken alone, produces a moderate degree of driving impairment which is related to the consumed THC dose. The impairment manifests itself mainly in the ability to maintain a steady lateral position on the road, but its magnitude is not exceptional in comparison with changes produced by many medicinal drugs and alcohol. Drivers under the influence of marijuana retain insight in their performance and will compensate, where they can, for example, by slowing down or increasing effort. As a consequence, THC's adverse effects on driving performance appear relatively small."

...

More specifically, alcohol impaired both vehicle handling and traffic maneuvers. Marijuana, administered in a dose of 100 g/kg THC, on the other hand, did not significantly change mean driving performance as measured by this approach. Subjects' ratings of driving quality and effort to accomplish the task were strikingly different from the driving instructor's ratings. Both groups rated their driving performance following placebo as somewhat better than 'normal'. Following the active drug, ratings were significantly lower (35%, p.009) in the marijuana, but not (5%, ns) in the alcohol group. Perceived effort to accomplish the driving test was about the same in both groups following placebo. Following the active drug, a significant (p.033) increase in perceived effort was reported by the marijuana, but not the alcohol group. Thus, there is evidence that subjects in the marijuana group were not only aware of their intoxicated condition, but were also attempting to compensate for it. These seem to be important findings. They support both the common belief that drivers become overconfident after drinking alcohol and investigators' suspicions that they become more cautious and self-critical after consuming low doses of THC, as smoked marijuana. Drug plasma concentrations were neither related to absolute driving performance scores nor to the changes that occurred from placebo to drug conditions. With respect to THC, these results confirm the findings in previous studies. They are somewhat surprising for alcohol but may be due to the restricted range of ethanol concentrations in the plasma of different subjects. DISCUSSION The results of the studies corroborate those of previous driving simulator and closed-course tests by indicating that THC in inhaled doses up to 300 g/kg has significant, yet not dramatic, dose-related impairing effects on driving performance (cf. Smiley, 1986).