Public Roads: A Journal of Highway Research and Development, Vol. 42 No. 1

Woo, Dah-Cheng; Sundberg, Donald; Culp, James D.; Labrum, Willard D.; Farr, Ralph M.; Kennedy, William J. Jr.; Gibson, David · 1978 · ROSA P / United States. Government Printing Office

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Summary

This document comprises two articles from the June 1978 issue of *Public Roads*, a journal of the Federal Highway Administration. The first article, "Bicycle-Safe Grate Inlets" by Dah-Cheng Woo, addresses the conflict between standard parallel-bar storm drain grates and bicycle safety. As bicycles became more prevalent, the narrow wheels of cyclists were prone to catching in the longitudinal bars of traditional grates, causing accidents. The research, conducted by the U.S. Bureau of Reclamation for the FHWA, aimed to identify grate designs that were safe for cyclists and pedestrians, structurally sound, hydraulically efficient, self-cleaning, and economical to manufacture. The study evaluated fifteen grate designs through three phases: structural analysis, safety testing, and hydraulic testing. Safety tests involved 539 runs by adult and child cyclists on wet grates to simulate worst-case conditions. Hydraulic tests were conducted in a full-scale flume to measure drainage efficiency and debris handling. The results identified three superior designs: a curved vane grate, a parallel bar grate with 1-1/8 inch spacing and transverse spacers, and a parallel bar grate with 1-7/8 inch spacing and transverse rods spaced at 4 inches. These designs provided adequate safety for cyclists while maintaining high hydraulic efficiency. The study noted a trade-off where grates rated highest for bicycle safety often performed lower in debris handling, allowing designers to select based on specific site conditions. The second article, "Map Displays for Traffic Systems" by Donald Sundberg, examines the design and function of central map displays used in traffic control centers. These displays serve to provide operators with instantaneous recognition of system failures and a real-time overview of traffic conditions. The article details various fabrication techniques, including enlargements of existing maps, custom artwork on Mylar, and mosaic tile displays. It emphasizes human factors engineering, noting that display size, scale, and color selection are critical for operator efficiency and visual comfort. For instance, high-contrast indicators on dark backgrounds reduce visual fatigue, and display scales typically range from 1:3,600 to 1:5,640 depending on the area coverage. The article concludes that incandescent indicators remain the most practical illumination technology due to their brightness, color versatility, and interface flexibility, despite the emergence of LED and LCD technologies.

Key finding

Three grate designs, specifically the curved vane grate and two parallel bar variants with specific spacing and transverse rod configurations, were identified as superior in bicycle safety, hydraulic efficiency, and fabrication cost.

Methodology

mixed_methods

Sample size: 539

Provenance

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

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• roadway lighting effects