Public Roads: A Journal of Highway Research and Development, Vol. 53 No. 2

Oliver, Morris B.; Trapani, Rita; Scheffey, Charles; Lane, Susan; Chollar, Brian; Zenewitz, Joseph A.; Boone, John G.; Tran, Kim Tranh; Anderson, David · 1989 · ROSA P / United States. Government Printing Office

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Summary

This document comprises two primary research articles from the September 1989 issue of *Public Roads*, addressing distinct issues in highway engineering: the implementation of audible pedestrian signals and the complexities of load equivalency in pavement design. The first article, by Morris B. Oliver, addresses the feasibility and standardization of audible pedestrian signals, which assist visually impaired individuals in crossing streets. Motivated by the increasing adoption of these devices in over 100 U.S. cities and the lack of uniform standards, the study aims to determine appropriate installation criteria and operational guidelines. The research methodology involved a comprehensive literature review and a 1988 feasibility study funded by the Federal Highway Administration (FHWA). Data were gathered through surveys and interviews with traffic engineers, manufacturers, audiologists, and visually impaired individuals. The study highlights the Committee for the Removal of Architectural Barriers (CRAB) evaluation system, which uses a 12-factor scoring model to prioritize intersections based on safety, traffic conditions, and proximity to facilities for the blind. The findings identify two dominant device types: the Mallory Sonalert buzzer, common in the eastern U.S., and the Traconex bird-call device, prevalent in the west. Oliver concludes that audible signals are feasible but should be reserved for complex intersections near key facilities. The article recommends establishing uniform operational standards, such as requiring distinct sounds for different crossing directions and ensuring devices are pedestrian-actuated to minimize noise pollution, to prevent confusion and enhance safety. The second article, by Rita Trapani and Charles Scheffey, examines issues surrounding load equivalency factors (LEFs), which estimate pavement damage caused by truck traffic. The research is motivated by the limitations of the American Association of State Highway Officials (AASHO) Road Test data from the 1950s, which failed to account for modern variables such as diverse vehicle configurations, tire technologies, and environmental factors. The paper summarizes findings from a 1988 FHWA-sponsored workshop involving 70 international specialists. Key findings indicate that road profile roughness significantly influences dynamic wheel forces and pavement damage, with rougher surfaces exacerbating damage at higher speeds. The study also highlights inconsistencies in tire research, noting discrepancies in contact pressure distribution measurements between different laboratories and the inadequacy of current road simulators for complex vehicle-trailer combinations. The authors conclude that there is a critical need for distinct load equivalency models for different user classes, the integration of vehicle, tire, and pavement dynamic models, and the development of uniform definitions for pavement response. The article emphasizes that future research must address the interaction between road profiles, tire characteristics, and pavement dynamics to improve the accuracy of pavement life predictions.

Key finding

Audible pedestrian signals are feasible aids for visually impaired pedestrians but require selective installation at complex intersections using standardized criteria and operational guidelines to avoid confusion and ensure effectiveness.

Methodology

mixed_methods

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