Investigation of Driver Comprehension of Traffic Information on Graphical Congestion Display Panels using a Driving Simulator

Richards, Andy; McDonald, Mike; Fisher, Granville; Brackstone, Mark · 2004 · Crossref

DOI: 10.18757/ejtir.2004.4.4.4276

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Summary

This study investigates driver comprehension of Graphical Congestion Display Panels (GCDPs), which provide real-time traffic and journey time information to improve route choices and network efficiency. Commissioned by the UK Highways Agency, the research aimed to establish prototype design guidelines by evaluating whether drivers could readily understand various GCDP designs without excessive distraction. The study was motivated by the increasing adoption of such signs in Europe and Japan and the lack of agreed design standards, particularly regarding color coding, map orientation, and information density. The researchers conducted a laboratory experiment using a STISIM driving simulator to impose a driving workload on 60 licensed participants. Twenty distinct sign designs were tested, categorized into five types: link-based, text, graphical, graphical segmentation, and lane/junction-based. Signs were projected separately from the driving scenario for fixed durations of either four or six seconds. Data collection involved two methods: verbal interview questions asked during driving to measure immediate comprehension accuracy, and a post-experiment written questionnaire assessing perceived usefulness, identified problems, and understanding. The analysis examined the effects of viewing time, question timing (before vs. after sign exposure), and driver demographics, including age, gender, mileage, experience, and map-reading ability. Results indicated that no single sign design was superior, but significant differences existed between types. Link-based signs (specifically Sign 11) and text-based signs (Sign 16) generally achieved higher comprehension and usefulness scores. Conversely, graphical segmentation signs (Signs 5, 12, and 20) performed poorly across all metrics due to excessive information density. Drivers asked questions before seeing the sign demonstrated significantly higher accuracy and rated signs as more useful, suggesting that prior knowledge or "priming" aids comprehension. Demographic analysis revealed that younger, less experienced, and lower-mileage drivers reported higher accuracy and usefulness, whereas older and more experienced drivers demonstrated better deep understanding. Good map-readers also showed higher accuracy. Viewing time did not significantly impact comprehension accuracy, indicating that four seconds was sufficient for information extraction. The study concludes that sign complexity directly impacts driver comprehension, with simpler designs yielding better results. The authors recommend specific prototypes for further testing: Sign 11 for link-based displays, Sign 16 for text-based, Sign 14 for graphical displays (preferring non-flashing and noting confusion over head-up orientation), and Sign 19 for lane/junction-based signs. The findings highlight the need for clear color coding and concise information presentation to ensure drivers can safely interpret traffic data. These recommendations provide a foundation for future field trials and the development of standardized GCDP design guidelines.

Key finding

Sign designs with lower information complexity, particularly link-based and specific graphical formats, resulted in significantly higher driver comprehension and perceived usefulness compared to complex segmentation designs.

Methodology

simulator

Sample size: 60

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• signage environment
• road complexity
• traffic density
• external distraction
• sign visibility legibility

Information type

What kind of knowledge this paper contributes, grouped by family — independent of topic (what it is about) and method (how it was studied).

• Applied Guidance: design guidelines