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Study Goals and Methodology

Project Goals

The Motorcycle Crash Causation Study (MCCS) is meant to provide insight into the causative factors that lead to motorcycle crashes in the United States. A comprehensive database of approximately 1,600 data elements was created from a collection of real-world motorcycle crash investigations and interviews of riders with similar risk factors. A research effort of this scale has not been conducted in the United States in 30 years. During this time, both the rider demographics and the motorcycles themselves have changed considerably and this new data source will make it possible to identify contemporary trends associated with motorcycle crashes. Study results may lead to the development of new roadway countermeasures, educational programs, and sound policy decisions that are rooted in a data-driven assessment of motorcycle safety.

"Crash investigators examine a crashed motorcycle."
Figure 1. Crash investigators examine a crashed motorcycle.

Project History

In 1999, motorcycle rider fatalities accounted for 6 percent of all crash-related fatalities in the United States. By 2005, that figure had climbed to 11 percent. Because of this alarming trend, the U.S. Congress approved Federal funding for a motorcycle crash causation study as part of the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU). The legislation specified that the Department of Transportation provide a grant to the Oklahoma Transportation Center to perform the research. In addition, the legislation required that the project use the Organisation for Economic Co-operative Development (OECD) data collection protocol. The OECD methodology refers to the Common International Methodology, comprised of an onscene and indepth crash investigation protocol for motorcycle crashes. The Federal Highway Administration (FHWA) was selected to oversee the project, and in 2006, the agency established a cooperative agreement between Oklahoma State University (OSU) and FHWA to conduct the study. Since then, an effective research plan was developed, and complicated issues associated with the collection of the large data set were addressed. The study’s data collection effort was completed in 2016.

OECD Methodology

The OECD methodology for onscene indepth motorcycle accident investigations was developed as an international standard to be used when conducting large motorcycle crash causation studies. The methodology requires data collection for motorcycle crashes that result in injuries to the rider. In total, approximately 1,600 data elements are collected for each case. The collected data elements include information on the motorcycle type, rider demographics, roadway characteristics, traffic details, alcohol use, rider behaviors, and many other factors related to the crash event. The crash investigations include onsite physical investigations, onsite interviews with crash participants (when possible), follow-up vehicle inspections, follow-up interviews, and injury data collection. In addition, the protocol requires that control data be collected on types of drivers with similar at-risk characteristics. This involves interviews of riders who were not involved in crashes, but who were exposed to similar riding environments. To accommodate this requirement, investigators revisit the site of the investigated crash one week later, at the same time of the day, to obtain information from motorcycle riders who were not involved in a crash. The use of the control population dramatically increases the statistical scope of the data by providing a comparison population to be used in the calculation of risk measures such as odds ratio and relative risks. The breadth and completeness of this methodology is designed to produce a data resource that can be used to conduct insightful and statistically viable research. The OECD methodology has been successfully implemented in motorcycle crash studies in Europe and Asia, and the National Highway Traffic Safety Administration (NHTSA) pilot study shows that it can work in the United States as well.

"Crash investigators take measurements at the scene of a motorcycle crash."
Figure 2. Crash investigators take measurements at the scene of a motorcycle crash.

NHTSA Pilot Study

In anticipation of the mandate for a MCCS, NHTSA awarded a contract to conduct a motorcycle crash causes and outcomes pilot study to serve as a feasibility and project-development effort that would support the larger MCCS effort. The pilot included hiring crash investigation personnel, developing investigator training documents, developing data collection documentation, developing relationships with local law enforcement agencies, and making recommendations based on the findings of the pilot. The pilot study was conducted during a 3-month period in 2008 in Orange County, CA. A total of 23 crash investigations were completed. The final report, NHTSA Motorcycle Crash Causes and Outcomes: Pilot Study, was completed in the summer of 2010, and the resulting products and recommendations were used to develop the final work plan for the larger MCCS effort.

Data Collection

OSU established agreements with the team that developed and conducted the NHTSA pilot study. This team includes some of the most experienced motorcycle crash investigation experts in the world. They have developed a detailed and proven work plan for conducting the MCCS according to the requirements of the OECD protocol. As laid out in the work plan, data collection was conducted in Orange County, CA. This location resembles a cross-section of American motorcycle riding environments. There are both rural and urban regions; flat land and rolling hills; and daily commuters and leisure riders, therefore, the data collected from this region should reflect many of the same causative factors that produce motorcycle crashes across the country. In addition, the work plan called for the crash investigators to be on call 24 hours per day, 7 days per week (24/7), so that they could respond to all crash notifications. At the scene (onscene), they documented the crash scene and conducted interviews, after which all participants were provided with a certificate of confidentiality issued by the National Institutes of Health. If the onscene interviews could not be conducted or were incomplete, the investigator attempted to set up a follow-up interview at a later time. Detailed physical investigations of the crash scene, the crashed motorcycle, and rider helmets were conducted as well. For the control data, motorcyclists who rode by the crash location at a later date under similar conditions were flagged down to be interviewed.

Data collection was completed in 2016. The level of funding supported the investigation of 350 crash cases and the corresponding controls.

"A crash investigator inspects a crashed motorcycle."
Figure 3. A crash investigator inspects a crashed motorcycle.


To develop and define the scope of the MCCS, a project working group (PWG) was established. This group included individuals from key motorcycle organizations with an interest in motorcycle safety. The technical input from the PWG was used to develop an effective and comprehensive plan for the administration and focus of the project. The PWG met throughout the life of the project, ensuring that the needs of the greater safety community were addressed in this important research effort. The PWG members are affiliated with the following organizations:

PWG Member Affiliations

FHWA American Motorcycle Association Westat, Inc.
NHTSA Oklahoma State University Dynamic Research, Inc.
NTSB Oregon State University Dynamic Science, Inc.
ABATE of Indiana Motorcycle Accident Analysis  

Several organizations, including other Federal agencies, State departments of transportation (DOTs), and private industry provided funding to the MCCS. An FHWA Transportation Pooled Fund (TPF) project was established to support the collection of additional cases. Through this program, State DOTs may participate in the MCCS project. More information about TPF projects can be learned via the following website:

TPF Project Site: The Motorcycle Crash Causation Study