Approach-End Treatment of Channelization: Signing and Delineation

Rowan, Neilon J. · 1962 · ROSA P / Texas Transportation Institute. Texas A&M University

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Summary

This 1962 interim report by the Texas Transportation Institute evaluates the effectiveness of signing and delineation treatments for channelizing islands, aiming to improve safety, operational efficiency, and capacity. The research addresses the critical need for adequate advance warning and clear geometric definition of channelization to prevent hazardous driver maneuvers. The study comprises three distinct phases: a comparative analysis of curb delineation materials, an evaluation of "KEEP RIGHT" sign visibility and legibility, and an assessment of driver behavior responses to channelization treatments. In the delineation phase, researchers tested four materials—yellow paint with glass beads, reflective coating compounds, and prismatic reflectors—under controlled conditions on simulated island curbs. Prismatic reflectors demonstrated superior performance, remaining visible at distances three to four times greater than the coating-type materials. This advantage was attributed to higher reflection efficiency and the perpendicular mounting of reflectors relative to traffic flow. Field performance studies in urban and rural Texas locations confirmed the reflectors' effectiveness but identified maintenance issues, specifically the reduction of reflectivity due to road film accumulation during inclement weather, highlighting a need for protective mounting devices. The sign visibility study compared eight variations of "KEEP RIGHT" signs, including internally illuminated, externally illuminated, prismatic reflector, and standard beads-on-paint types. Tests measured recognition distance (visibility) and reading distance (legibility) at mounting heights of 3.5 and 7 feet. Results indicated that internally illuminated signs provided the greatest visibility and legibility, followed by prismatic reflector signs and externally illuminated signs. Standard beads-on-paint signs performed the poorest. Notably, mounting height did not significantly affect visibility or legibility under the tested conditions. The prismatic reflector sign was highlighted as a practical alternative due to its high visibility relative to its cost and the distinct visibility of its large arrow symbol. The driver behavior phase utilized Galvanic Skin Response (GSR) recorders and speed measurements to assess physiological and operational responses. The introduction of divisional island channelization caused a slight increase in driver tension, which further increased when special approach-end treatments, such as prismatic reflectors, were added. Traffic speed analysis revealed that drivers began decelerating at a greater distance from the intersection and did not resume normal speeds until clear of the channelized area. These findings underscore the importance of high-visibility delineation and signing to manage driver tension and ensure safe navigation through channelized zones.

Key finding

Prismatic reflectors were visible at distances three to four times greater than paint or coating materials, and internally illuminated signs provided superior visibility and legibility compared to all other sign types tested.

Methodology

lab_experiment

Sample size: 4

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
• emergency work zone conspicuity
• perceptual countermeasures
• roadway lighting effects