For IE 577 – Human Factors in Engineering – we were tasked with performing an original research project related to a human factors topic of interest. I have long wondered what makes bicycle tail lights effective on the road and which of the blinking or steady modes is ideal for visibility.

We combined off bike video analysis with on-bike testing and a survey to complete a PCA (Principal Component Analysis) and discern what light parameters were most aligned with subjective visibility ratings. The video analysis allowed us to measure the mean intensity, area, effective radius, peak intensity, and blink frequency. The subjective survey utilized a paired comparison of two on-bike videos adjacent to one another asking respondents to select the more visible light. The win rate of each light was then used to rank the lights and modes.

Flashing modes generally outperformed steady modes. Light peak intensity and effective radius most strongly correlated with light rank. The effective radius of two models is shown in the figure below.

Meredith Burke, Lily Meyer, Claire Soller, and Abby Trent all contributed to this project.