Alcohol has extremely harmful effects upon the processes involved in motorcycle operation. These effects begin long before a rider becomes intoxicated. Let's look at each of the processes involved in riding a motorcycle safely.

Scan

The speed with which highway and traffic conditions can change necessitates an active process of "searching" or "scanning" the environment around the motorcycle constantly.Alcohol does not have much effect upon the search process itself, at least not until large amounts of alcohol are consumed. However, research has shown conclusively that alcohol has a very harmful effect upon the ability of riders to divide their attention between searching the environment and operating the motorcycle. They can do either alone, but not both together. What typically happens is that riders become preoccupied with the bike and the path immediately in front of it. They just don't notice what's going on around them. This happens at BACs of .05%, that is, with a couple of drinks in the bloodstream. The rider's tendency to stop searching the environment can have terrible consequences. Failing to notice what is going on around the motorcycle is one of the major causes of motorcycle accidents.

Identify

Visual search of scanning can only direct the operator's vision toward potential hazards and the highway traffic environment. To cope with hazards, riders must be able to identify them. And to do this, they must be able to see clearly. Ordinary visual acuity (the ability to see clearly) doesn't begin to show the effects of alcohol until one is almost intoxicated. However, there are two aspects of visual acuity that are extremely sensitive to alcohol.

One aspect of visual acuity that is affected by small amounts of alcohol is the ability to see moving objects. Of course, for the motorcycle in motion, all objects around it are essentially moving objects. The ability to detect small moving objects, such as a car in the distance or a small child on the sidewalk, is affected by as little as one drink in the bloodstream.

Another aspect is night vision. The ability to see clearly under nighttime conditions is affected by as little as one drink. So, too, is the ability to handle glare from the headlights of oncoming vehicles. With two to three drinks in the system, the ability to see clearly at night is diminished by as much as one-third.

Predict and Decide

The ability to exercise good judgment in making decisions is one of the first things to be impaired by alcohol. Alcohol affects decisions about such things as how fast to drive, whether to pass the vehicle ahead, whether to give way to another vehicle, as well as many other decisions that are truly life-and-death matters. One of the very first things alcohol does is lessen that sense of self-preservation that helps people use good judgment in dealing with risky situations. At the same time it also affects the judgment of how well or how poorly they're riding. The result of these double-barreled effects is that while the drinking riders get worse and worse, they think they are getting better and better; therefore, they take greater and greater risks.

Unfortunately, the loss of judgment and sound decision-making starts with the first drink and can itself result in more and more drinking. That is what makes it so dangerous.

Execute

Whatever decisions riders reach - good or bad - are executed in the handling of the motorcycle. Those aspects of execution most strongly affected by alcohol are:

Reaction Time: Alcohol produces slower reaction. Actually, simple reactions to things like brake signals or traffic lights are not much affected. What suffers particularly is the ability to react quickly when there is a choice of things to do, e.g., swerve right or left, turn or brake. Alcohol can leave people so confused that they don't do anything at all.

Coordination: The ability to control a motorcycle demands a high degree of eye, hand, and foot coordination. Alcohol can severely interfere with this coordination. The effects of alcohol will show up in errors such as clashing gears during a shift or lurching to a stop; slowness - taking longer to complete a maneuver because of difficulty carrying out the coordination quickly; and corrections - having to jockey the handlebars or throttle back and forth to maintain a fixed course or speed.

Balance: A sense of balance is obviously important in operating a two-wheel vehicle. It is also one of the senses affected by alcohol (which is why it is frequently used as a test of sobriety).

While anyone's execution is affected by alcohol, the effect is most severe among inexperienced riders. People who have been riding for many years may not be visibly affected until they are almost intoxicated. However, those with only a few years experience, and those who don't ride a great deal during the course of a year, will show effects with as few as one or two drinks in their systems.