Bicyclist Behavior Survey Finds California Riders Oppose Mandatory Helmet Law

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MTI researchers analyzed 800+ survey responses to understand public opinion about mandatory helmet use laws in California
November 2, 2021
San José, CA

At the end of 2019, the National Transportation Safety Board recommended the introduction of an all-ages helmet law to reduce fatalities involving cyclists. Although the benefits of wearing helmets in protecting cyclists against trauma have long been established, helmet use is still limited, and some opposition remains against mandatory helmet use, particularly for adults. New Mineta Transportation Institute (MTI) research, Exploring the Relationship Between Mandatory Helmet Use Regulations and Adult Cyclists’ Behavior in California Using Hybrid Machine Learning Models, explores perceptions of adult cyclists regarding mandatory helmet use to understand cyclists’ behavior and determine the impact of mandatory helmet use on cycling rates.

More than eight hundred valid responses were gathered for this study. The major takeaways include: 

  • 70% of respondents do not support implementation of a mandatory bicycle helmet law in California.

  • The cyclists with the highest frequency of bicycle use constitute the highest proportion of opposers to mandatory bicycle helmet law.

  • Understanding the benefits of using a helmet and the risks of cycling may encourage helmet use.

  • Aesthetic, comfort of helmets, and peer conceptions are among the barriers of wearing helmets.

  • Frequency of helmet use, education level, gender, marital status, as well as beliefs about helmet use and age are the most significant predictors of change in cycling rate should a bicycle helmet law be implemented. 

“Our analysis shows that the main objections against a bicycle helmet law are: (1) it discourages ridership, creating public health and environmental concerns, (2) it favors inequality due to increased costs for cyclists as well as required enforcement by the police, (3) it violates people's rights and freedom of choice, and (4) its enforcement will deplete police resources,” explain the study’s authors. 

Studies conducted in France and British Columbia investigated an alternative to mandatory helmet laws for adults, which suggested that helmet usage campaigns are effective tools to increase compliance in the absence of a law. Based on the findings of this study, public service campaigns coupled with investments in public infrastructure can keep cyclists moving safely. 



At the Mineta Transportation Institute (MTI) at San Jose State University (SJSU) our mission is to increase mobility for all by improving the safety, efficiency, accessibility, and convenience of our nations’ transportation system. Through research, education, workforce development and technology transfer, we help create a connected world. Founded in 1991, MTI is funded through the US Departments of Transportation and Homeland Security, the California Department of Transportation, and public and private grants, including those made available by the Road Repair and Accountability Act of 2017 (SB1). MTI is affiliated with SJSU’s Lucas College and Graduate School of Business.

Dr. Fatemeh Davoudi is an Assistant Professor in the Dep. of Aviation and Technology at San Jose State University. Dr. Davoudi is currently leading the Machine Learning & Safety Analytics Lab. Dr. Maria Chierichetti is an Assistant Professor in the Dep. of Aerospace Engineering at San Jose State University. Her current research interests focus on integrating machine learning to current analysis tools to improve the safety of transportation systems.


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