banner of Methodology for Determining Motorcycle Operator Crash Risk and Alcohol Impairment

4. Research Priorities

Highest Priority Methodologies

Methodologies discussed in this section were determined to be the best candidates for future research.

Lowest Cost Category < $250,000

Simulation

Simulation would provide a relatively low-cost method of determining the effects of alcohol impair­ment on motorcycle operation. Unlike automotive simulators, motorcycle simulators can provide reasonably high fidelity motion cues without using expensive motion-base platforms.  This is largely because real motorcycles, like aircraft, are “bank-to-turn” vehicles, which means that the operator experiences and senses mainly visual cues, rather than a combination of visual and motion cues that car drivers experience. Simulation would not provide risk curves directly comparable with those from drinking/driving case-control studies. However, it could provide crash risk curves for involvement in simulated crashes.  If a simulated driving task was used along with a simulated riding task, it would be possible to compare the relative risk curves for the two as a way to determine the differential effect of alcohol impairment on motorcycling. It was also suggested that testing a sample of riders at relatively low BACs, performing both simulated low-speed riding tasks and actual low-speed riding tasks, could help establish the validity of simulation in measuring rider performance. In this type of study, relative risk curves could be produced by determining the number of crashes or near misses for riders at BACs = .02 g/dL, .04 g/dL, .06 g/dL, and .08 g/dL compared to their performance at BAC = .00 g/dL.

Induced Exposure

The general consensus regarding an induced exposure study for motorcycles is that this type of study does not lend itself well to motorcycle crashes. Determining culpable motorcyclists from nonculpable motorcyclists will require some additional work, and may ultimately not be viable. This method, however, can be accomplished with existing data and probably at very little cost. It was suggested that if an induced exposure study is done, a first step would be to compare any “culpable” group and “nonculpable” group of motorcycle riders to determine whether the two groups were similar with respect to demographic variables. If they are not, then it will be difficult to separate the effects of alcohol from the effects of the general differences between the two samples.

Medium Cost Category $250,000 to $500,000

None.

Highest Cost Category $500,000 +

It should be noted that the cohort study, while being rated as highly valid, would certainly be too expensive to seriously consider funding, and is therefore not considered a high priority methodology by the study authors.

Contemporary Case Control

This methodology is probably the most scientifically valid of all methods that might be practically implemented. The Contemporary Case Control methodology was used in the landmark motorcycle crash study conducted by Hurt et al. (1981), though this study did not conduct sufficiently detailed alcohol data to generate relative-risk curves. This methodology was used by Borkenstein et al. (1974) to create the drinking-driving relative-risk curves that have been used for the past 25 years to under­stand the effects of alcohol on driving. There was a high level of agreement among panel members and project staff that a Contemporary Case Control study, if conducted properly, would be the best way to determine the relative risks of operating a motorcycle at various BAC levels.

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