Visual attention characteristics of supplementary safety signs and their nudge effect on risk identification in oil and gas pipelines

The complex working environment of oil and gas pipelines, characterized by widely distributed risk sources, often hinders employees' ability to identify risks, which is a key cause of workplace safety incidents. Supplementary safety signs act as important information carriers that complement the content of main safety signs, effectively nudging employees toward better risk identification behavior. However, their effectiveness is significantly influenced by core attributes such as color, shape, and format, but systematic research on this issue is currently lacking in the oil and gas pipeline industry. This study aims to identify how different attributes of supplementary safety signs influence employees' visual attention and nudge risk identification behavior, providing a theoretical framework for optimizing safety sign design and enhancing hazard recognition efficiency in oil and gas pipeline enterprises.

Based on a major oil and gas pipeline network enterprise in China, this study selected three representative operational scenarios: anti-corrosion, pressure testing, and maintenance and repair of pipelines and storage tanks. Using 38 risk identification points as sign content, 18 groups of supplementary safety signs were designed following national standards. An orthogonal design was used to combine different attributes of color (red, blue, black) × shape (triangle, circle, rectangle) × format (text, icon). The study recruited 180 participants with at least 2 years of work experience in oil and gas pipelines, who were randomly divided into 18 groups to participate in the orthogonal experiments. A Tobii Pro Glasses 2 wearable eye tracker was used to collect four eye-tracking metrics: time to first fixation, first fixation duration, total fixation duration, and fixation count. Furthermore, two behavioral metrics—response time and accuracy of risk identification—were recorded. Multivariate analysis of variance (MANOVA), Least Significant Difference post hoc tests, and interaction plots were employed to systematically evaluate the main and interaction effects of color, shape, format, and their combinations on visual attention characteristics and behavioral nudge effects.

Color and shape were the primary drivers of visual attention orientation and behavioral accuracy. Specifically, red and triangular designs significantly shortened the time to first fixation (by 411 ms and 213 ms, respectively) and improved behavioral accuracy by 5.79% and 2.20%, respectively. Notably, color (Partial η² = 83.6%) and shape (Partial η² = 55.2%) exhibited the strongest main effects on time to first fixation. The format was the main driver of sustained visual attention. Specifically, text signs drew more engagement than icon signs, increasing first fixation by 363 ms, total fixation by 350 ms, and fixation count by 1.93. The findings also demonstrated that color and format were critical factors influencing risk identification response time. Red signs outperformed blue and black variations, shortening the response times by 564 ms and 540 ms, respectively. Similarly, icon signs shortened the response time by 878 ms relative to text signs. Color (Partial η² = 90.3%) and format (Partial η² = 96.3%) exhibited the strongest main effects on response time. Significant synergistic effects were observed among attributes: the red–triangle combination yielded the highest behavioral accuracy, outperforming blue and black combinations by 7.93% and 8.92%, respectively. Furthermore, the red–icon combination resulted in the fastest response time, reducing it by approximately 792 ms compared with blue–icon and black–icon combinations. Finally, shape and format interacted significantly regarding total fixation duration; triangles and circles attracted longer fixation durations in text format but shorter durations when paired with icons.

The color, shape, and format differentially influence employees' visual attention orientation, sustained attention, and risk identification nudge effects among employees in oil and gas pipeline enterprises. Red and triangular attributes rapidly capture attention and enhance behavioral accuracy, text facilitates sustained attention, and icons accelerate behavioral responses significantly. Synergistic designs further amplify these nudge effects. This study recommends that the oil and gas pipeline industry treat supplementary safety signs as independent management units using optimal color–shape–format combinations. The findings offer theoretical and empirical support for optimizing safety signage in high-risk, large-scale industrial scenarios. Future research should validate the generalizability of these findings in real-world operational settings.