Symbolic Sign for Oversized-Truck Route Signs

Walker, Jonathan; Alicandri, Elizabeth; Roberts, King · 1984 · ROSA P / United States. Department of Transportation. Federal Highway Administration

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Summary

This study addresses the need for a standardized symbolic sign to mark routes on the National Network of Highways where oversized trucks are permitted or prohibited, a requirement mandated by the Surface Transportation Assistance Act of 1982. Prior to this research, no standardized regulatory sign existed for this purpose, creating a need for a symbol that is easily visible, quickly recognizable, inherently meaningful, and distinct from existing signs such as the "No Trucks" symbol. The Federal Highway Administration conducted this evaluation to select the most effective candidate sign for informing both truck drivers and the general driving public. The research employed two laboratory experiments to evaluate six candidate symbolic signs: front-view narrow, front-view wide, rear-view narrow, rear-view wide, side-view long, and side-view double-trailer. Experiment 1 involved 60 subjects from the general public who were tested in a vision tunnel for visibility (distance at which the sign was identified as a truck, its view, and its oversized nature), intrinsic meaning, and preference. Experiment 2 involved 121 truck drivers recruited from a rest area, who were tested for recognition time (speed of decision-making), meaning, and preference using a slide projector in a mobile laboratory. Both experiments utilized permissive (green ring) and prohibitory (red ring with slash) versions of the signs. The findings indicated that the side-view, double-trailer sign was the superior candidate. In Experiment 2, truck drivers recognized the double-trailer sign significantly faster than other candidates, particularly the rear-view wide sign. While the side-view long sign had the greatest visibility distance in Experiment 1, the double-trailer sign achieved the highest scores for meaning and preference in both populations. Crucially, the double-trailer sign was the only candidate consistently identified as representing an "oversized" truck, whereas other signs were frequently confused with general truck route signs or the existing "No Trucks" sign. Both the general public and truck drivers overwhelmingly preferred the double-trailer sign. The study also noted that the green ring used for permissive signs caused confusion among truck drivers, many of whom misinterpreted it as prohibitory. The study concludes that the side-view, double-trailer sign is the best candidate for marking oversized truck routes because it effectively conveys the specific "oversize" message, is distinct from existing regulatory signs, and is highly preferred by users. The authors recommend adopting this symbol, while noting that further study is needed regarding the use of the green ring for permissive signs due to potential misinterpretation. The research provides empirical evidence supporting the selection of a specific symbolic design to improve traffic safety and regulatory compliance for oversized vehicle operations.

Key finding

The side-view double-trailer sign was the only candidate symbol consistently interpreted as indicating an oversized truck route by both the general public and truck drivers, and it achieved the fastest recognition times among truck drivers.

Methodology

mixed_methods

Sample size: 181

Provenance

The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via bulk_ingest_rosap on 2026-05-23 (6 acquisition events logged).

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

Topics

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• sign visibility legibility
• signage environment
• vehicle conspicuity