Visual Eye Gaze While Cycling: Analyzing Eye Tracking at Signalized Intersections in Urban Conditions

Understanding Cyclists' Visual Behavior Using Eye-Tracking Technology: A Systematic Review

Eye-tracking technologies are emerging in research aiming to understand the visual behavior of cyclists to improve their safety. These technologies gather real-time information to reveal what the cyclists look at and how they respond at a specific location and time. This systematic review investigates the use of eye-tracking systems to improve cyclist safety. An extensive search of the SCOPUS and WoS databases, following the PRISMA 2020 guidelines, found 610 studies published between 2010 and 2024. After filtering these studies according to predefined inclusion and exclusion criteria, 25 were selected for final review. The included studies were conducted in real traffic or virtual environments aiming to assess visual attention, workload, or hazard perception. Studies focusing on other types of road users or participants not involved in active cycling were excluded. Results reveal the important impact of road elements' design, traffic density, and weather conditions on cyclists' gaze patterns. Significant visual workload is imposed mainly by intersections. Along with the valuable insights into cyclist safety, potential biases related to small sample sizes and technological limitations were identified. Recommendations for future research are discussed to address these challenges through more diverse samples, advanced technologies, and a greater focus on peripheral vision.

Visual behavior of racing bike cyclists in multi-tasking situations

Distracted biking can have serious repercussions for the rider such as accidents. The purpose of the present experiment was to determine the effect of visually monitoring two parameters, the cadence, and the heart rate on a bike computer fixed on a racing bike, and simultaneously detect hazardous traffic situations. Individuals (n = 20) were instructed to ride a racing bike that was fitted onto a roller trainer. After conducting a bicycle step test to assess the maximal heart rate (HFmax), participants were assigned to a within subject-design on a separate day. They were instructed to perform the riding task in two single-task conditions (only watching the traffic at the video with occluded or without occluded bike computer), two multi-tasking conditions (monitoring the cadence of 70 RPM or 90 RPM, monitoring the heart rate, and observing the traffic) and one control condition (no instructions). Percentage dwell time of the eye movements, the constant error from the target cadence, keeping the heart rate in an interval of 50% - 70% of the HFmax, and percentage of the recognized hazard traffic situations were analyzed. The analysis indicated that monitoring the parameters on the bike computer induced no significant decline in perceived hazardous traffic situations.

Evaluation of bicyclist physiological response and visual attention in commercial vehicle loading zones

INTRODUCTION

With growing freight operations throughout the world, there is a push for transportation systems to accommodate trucks during loading and unloading operations. Currently, many urban locations do not provide loading and unloading zones, which results in trucks parking in places that obstruct bicyclist's roadway infrastructure (e.g., bicycle lanes).

METHOD

To understand the implications of these truck operations, a bicycle simulation experiment was designed to evaluate the impact of commercial vehicle loading and unloading activities on safe and efficient bicycle operations in a shared urban roadway environment. A fully counterbalanced, partially randomized, factorial design was chosen to explore three independent variables: commercial vehicle loading zone (CVLZ) sizes with three levels (i.e., no CVLZ, Min CVLZ, and Max CVLZ), courier position with three levels (i.e., no courier, behind the truck, beside the truck), and with and without loading accessories. Bicyclist's physiological response and eye tracking were used as performance measures. Data were obtained from 48 participants, resulting in 864 observations in 18 experimental scenarios using linear mixed-effects models (LMM).

RESULTS

Results from the LMMs suggest that loading zone size and courier position had the greatest effect on bicyclist's physiological responses. Bicyclists had approximately two peaks-per-minute higher when riding in the condition that included no CVLZ and courier on the side compared to the base conditions (i.e., Max CVLZ and no courier). Additionally, when the courier was beside the truck, bicyclist's eye fixation durations (sec) were one (s) greater than when the courier was located behind the truck, indicating that bicyclists were more alert as they passed by the courier. The presence of accessories had the lowest influence on both bicyclists' physiological response and eye tracking measures.

PRACTICAL APPLICATIONS

These findings could support better roadway and CVLZ design guidelines, which will allow our urban street system to operate more efficiently, safely, and reliable for all users.

Seeing Is Believing: Using Eye-Tracking Devices in Environmental Research

OBJECTIVES

This article aims to provide methodological guidance for research that uses eye-tracking devices (ETDs) to study environment and behavior relationships.

BACKGROUND

Vision is an important human sense through which people acquire a large amount of environmental information. ETDs are tools for detecting eye/gaze behaviors, facilitating better understanding about how people collect visual information and how such information is related to emotions and psychological states. However, there is a lack of guidance for the application of ETDs to environment and behavior studies.

METHODS

A literature review was conducted on articles reporting empirical studies that used ETDs. The data were extracted and compiled, including information such as research questions, research design, types of ETDs, variables measured, types of physical environment (or visual stimuli), stimuli durations, data analysis methods, and so on.

RESULTS

Fifty articles were identified. The main research topics were related to urban and landscape environments, and architecture and interior spaces. Most of the research designs were experimental or quasi-experimental designs, with a few cross-sectional studies. The majority types of ETDs were screen-based ETDs, followed by mobile ETDs (glasses). Main variables were gaze fixations, fixation durations, and scan paths. Typical types of stimuli included images, videos, virtual reality, and real environments and/or objects.

CONCLUSIONS

Guidance for eye-tracking research on environment and behavior was developed based on the literature review results, to provide direction for determining research questions, selecting appropriate research designs, establishing participant inclusion and/or excluding criteria, collecting and analyzing data, and interpreting research results.

Urban Mid-Block Bicycle Crossings: The Effects of Red Colored Pavement and Portal Overhead Bicycle Crossing Sign

This paper aims to investigate the effectiveness of some mid-block bicycle crossing elements by analyzing the drivers’ behavior, when approaching the bicycle crossings in a real road experiments with 18 participants. The eye-tracking instrument has been used to monitor the driver’s visual behavior during the test in an instrumented vehicle with GPS (global positioning system) and an inertial measurement unit (IMU). In particular, the drivers’ gaze was investigated frame by frame while approaching the mid-block bicycle crossings. The results showed that the red colored pavement increased the visibility of the mid-block crossing zone to 65.3% with respect to zebra crossing 59.6%. The drivers’ visual field was also narrowed by the portal overhead bicycle crossing sign and, consequently, drivers reduced their velocity and looked more to the vertical signs by 28%. The drivers’ speed reduction helped drivers to see the mid-block crossing elements from a greater distance with a higher fixation duration.

How do pedestrians distribute their visual attention when walking through a parking garage? An eye-tracking study

We examined what pedestrians look at when walking through a parking garage. Thirty-six participants walked a short route in a parking garage while their eye movements and head rotations were recorded with a Tobii Pro Glasses 2 eye-tracker. The participants' fixations were then classified into 14 areas of interest. The results showed that pedestrians often looked at the back (20.0%), side (7.5%), and front (4.2%) of parked cars, and at approaching cars (8.8%). Much attention was also paid to the ground (20.1%). The wheels of cars (6.8%) and the driver in approaching cars (3.2%) received attention as well. In conclusion, this study showed that eye movements are largely functional in the sense that they appear to assist in safe navigation through the parking garage. Pedestrians look at a variety of sides and features of the car, suggesting that displays on future automated cars should be omnidirectionally visible. Practitioner summary: This study measured where pedestrians look when walking through a parking garage. It was found that the back, side, and wheels of cars attract considerable attention. This knowledge may be important for the development of automated cars that feature so-called external human-machine interfaces (eHMIs).