Bicyclists vs. Right Turn Vehicles: Optimizing Design Based on Conflict Risk Data

Project Description

While protected bike lanes are very safe for users while cycling behind the protection, cyclists must cross intersections where there is no physical protection. Between 2014 and 2016, 44% of bicyclist fatalities in urban areas occurred at intersections. Of the intersection fatalities during that period, vehicle right turn vs bicyclist in the same direction ("right hook" crashes) were listed in the Top 7 most common crash types.[1] There is a lack of data on crashes and on near-misses to inform facility design.

This project is seeking to quantify the safety effects of intersection design treatments recommended in national guidance and evaluate other key contextual elements known to impact bicyclist safety[2] by studying the frequency and severity of detected conflict events. This study is being done in collaboration with other North American cities to conduct similar, parallel studies so that findings can be shared and generate a database for future research.

More information:

[1] National Academies of Sciences, Engineering, and Medicine, 2020. Guidance to Improve Pedestrian and Bicyclist Safety at Intersections. Washington, DC.

[2] Dai, B., Dadashova, B., 2021. Review of contextual elements affecting bicyclist safety. Journal of Transport & Health 20, 101013.

Project Need

DDOT has constructed over 8 miles of protected bike lanes in the last 18 months and is now charged with construction of 10 miles of protected cycling infrastructure each year starting in 2022. In this context there is a heightened interest in making sure these facilities are as safe as possible, especially as we strive to attract new riders of varying ages and skill levels onto the cycling network. DDOT is not alone in this challenge. Protected bike lane mileage in North American cities has grown by more than 600% since 2011,[1] illustrating the importance of safe, evidence-based design guidance.

[1] NACTO, 2019. Don’t Give Up at the Intersection. New York.

Desired Outcome & Expected Benefits

Risk diagnostic report for ten (10) intersections + contribution to an open source data repository and a final report summarizing findings and implications for design.


Site and Attribute Identification and Data Repository Development

  • PI shall collaboratively develop a study site type matrix and metadata attribute list with all study participants.
  • DDOT will then select ten (10) sites for inclusion in the study. The PI shall coordinate among agencies to ensure adequate distribution of sites across the study site type matrix.
  • PI shall design and develop the study data repositories, including expectations for data storage, privacy, and open access at the end of the study. The PI shall coordinate with leading researchers and developers of design guidance to ensure data attributes and formats will support the development of the next generation of design guidance

Data Collection

  • DDOT will collect between 60 and 168 hours of video at the ten (10) selected locations.
    • The PI shall provide all participating cities with standard parameters for how data should be collected and the minimum video specifications to allow for data analysis.
  • The PI shall also define a list of metadata attributes for each intersection that will allow for the execution of the original study design. DDOT will provide said metadata attributes for its ten (10) locations and as well as five (5) years of crash data for the locations.

Data Analysis

The PI shall use video analytics technology to measure trajectories of all road users and to measure conflicts between right turning vehicles and cyclists based on these trajectories for at least 600 hours of video (12 hours/day for 5 days/location). The results of this analysis shall be provided as a risk diagnostic report specific to each location.

Final Report

The PI shall combine the data from all participating cities and develop a draft final report that summarizes key results and findings together with their implications for design and future research.

Using the data from all participating peer cities, the PI shall create and publish open data repositories with the combined results from all cities.

Project Oversight

DDOT Stakeholders

Peer Reviewers

Meeting notes

Quarterly updates

QuarterProgress this quarterIssues Encountered
FY22 Q1Identified the 10 intersectionsNeed to find a contracting method
FY22 Q2

Project Materials

Any relevant materials, including problem statement, scope of work, interim deliverables, reports, data can be uploaded below.

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