University of Minnesota Driven to Discover
U of MNUniversity of Minnesota
Center for Transportation Studies

Motorcycles and alcohol: Research examines a dangerous combination

Deputy Secretary of Transportation Thomas Barrett (seated) discusses motorcycle safety with researchers Craig Shankwitz and Janet Creaser.

Deputy Secretary of Transportation Thomas Barrett (seated) discusses motorcycle safety with researchers Craig Shankwitz and Janet Creaser.

This summer, with gas prices at an all-time high and warm weather beckoning riders to hit the road, motorcycles and scooters are more popular than ever. But statistics from the National Highway Traffic Safety Administration (NHTSA) show that while motorcycles account for only three percent of motor vehicle registrations, they make up 11 percent of total motor vehicle fatalities.

Researchers from the HumanFIRST Program and the Intelligent Vehicles Laboratory recently collaborated to study the effects of alcohol on motorcyclists, taking advantage of the programs’ access to unique research facilities and expertise in monitoring driver performance.

Deputy Secretary of Transportation Thomas Barrett, during a recent visit to the University of Minnesota, had the opportunity to take a close look at the specially equipped motorcycle at the heart of the project. On hand to brief Barrett were principal investigator Janet Creaser of the HumanFIRST Program and Intelligent Vehicles Lab director Craig Shankwitz.

Most testing of alcohol impairment has been done in passenger vehicles and has not focused on the unique skills required to ride a motorcycle, according to Creaser. However, due to the increased number of motorcycle riders and the known crash risk for alcohol impaired riders, it is important to study the effects of alcohol on riding skills.

With funding from NHTSA, the Minnesota study aimed to fill a significant gap in research on the effects of alcohol consumption.

Studying safety, safely

While a large body of research has been devoted to detailed analysis of how alcohol interferes with automobile operation, relatively little work has been completed on the question of how alcohol affects the skills required to operate a motorcycle. One factor in this discrepancy is the difficulty in accurately evaluating motorcycle operation skills without endangering the safety of the rider. Realistic driving simulators based on motorcycles rather than four-wheeled vehicles are virtually unknown, and in-vehicle testing is restricted by the obvious hazards facing an impaired rider, as well as strict laws prohibiting vehicle operation while intoxicated.

To overcome these restrictions, the Minnesota team incorporated three critical components into their research methodology: a purpose-built mechanical safety system to safeguard the test subjects; a remote data-acquisition system to gather detailed information on all relevant aspects of the subjects’ performance; and a testing facility that could legally and safely accommodate inebriated riders.

The motorcycle selected for research use, a model typical of the bikes chosen by many riders today, was first equipped with a system of mechanical outriggers capable of preventing it from falling sideways in the event that a rider lost his balance. During normal operation, the outriggers are free to move up and down as the cycle turns; if the cycle leans too far to either side, however, they prevent it from tipping over completely.

Capturing the complex data needed to characterize driver performance was the task of the Motorcycle Data Acquisition system, or MoDAQ. Based on a system developed by the Intelligent Vehicles Lab for automotive research, the MoDAQ is an onboard, mobile system that integrates data from a range of sensors. The system includes sensors that monitor the operation of the cycle’s controls—throttle, brakes, and steering; accelerometers that measure forward and lateral movements; and a helmet equipped with a miniature video camera and inertial measurement units. Synchronizing the outputs from all these sensors gives researchers a complete picture of driver performance and vehicle response.

Even with its added safety features, operating the motorcycle with alcohol-impaired research participants would still have been prohibited by Minnesota law, which applies to private driving courses and tracks as well as to public roads. Fortunately, one driving course in Minnesota is specifically exempt from the state law: the Minnesota Highway Safety and Research Center in St. Cloud. The facility is one of several closed courses used in HumanFIRST research.

The research team recruited 24 male study participants who had a minimum of five years of motorcycling experience and drank alcohol at least once a week but had no history of alcohol dependence. After training designed to familiarize the riders with the research motorcycle, the riders participated in three half-day test sessions during which they drank alcohol to reach a blood-alcohol concentration of .02, .05, or .08 g/dL (the legal limit in all 50 states), or were given a placebo (alcohol applied to the rim of a glass containing a non-alcoholic beverage).

After consuming the alcoholic beverage or the placebo, the participants rode through a test course developed in collaboration with motorcycle instructors from the Minnesota Motorcycle Safety Center. The course included a variety of tasks, ranging from routine riding situations to emergency maneuvers. Data from both baseline (non-alcohol) rides and rides after consuming alcohol were gathered for each participant, enabling the researchers to compare the effects of different amounts of alcohol consumption.