DIRECT Operational Field Test Evaluation: Natural Use Study: Part 1: Subject Stated Response

Reed, Thomas B.; Underwood, Steven Eugene; Richeson, Rebecca; Hanafi, Taufik · 1998 · ROSA P / University of Michigan. Intelligent Transportation Systems Research Laboratory

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Summary

This paper reports the findings of Part I of the DIRECT (Driver Information Radio using Experimental Communication Technologies) operational field test, a natural use study sponsored by the Michigan Department of Transportation and the Federal Highway Administration. The research addresses the evaluation of four low-cost, voice-based traffic information delivery systems: Automatic Highway Advisory Radio (AHAR), Low Power Highway Advisory Radio (LPHAR), telephone, and Radio Data System with Subsidiary Communications Authority (RDS/SCA). The primary motivation was to assess the potential for widespread deployment of these systems, which offer route-specific information at minimal incremental cost compared to expensive Advanced Traveler Information Systems. The study aimed to answer three core questions: what drivers think of these systems, how their behavior changes in response, and how these choices affect trip characteristics. The study employed a quasi-experimental natural use design involving 174 commuters who drove project-supplied vehicles equipped with one of the four systems for eight weeks along the I-75 corridor to downtown Detroit. Participants were randomly assigned to one of four test groups or a control group, with data pooled across seven periods to manage resources. To control for external variables, subjects were assigned to cohorts traveling at similar times to encounter comparable traffic conditions. Data collection included detailed before-and-after questionnaires, telephone interviews, and driver notebooks. Additionally, objective behavior data was recorded via in-vehicle tracking equipment that logged radio frequencies, cellular phone usage, and vehicle location every five seconds. All subjects had access to a baseline of commercial radio, changeable message signs, and television traffic reports. The results indicate that subjects were highly satisfied with and reliant on commercial radio, while expressing dissatisfaction with all four DIRECT systems, primarily due to perceived unreliability. Drivers felt the DIRECT systems did not operate as intended, which negatively influenced their perception of other performance metrics. Despite this, the DIRECT systems were rated higher than commercial radio on specific attributes such as being "route-specific," "available on demand," and "attention-catching." The RDS/SCA system performed slightly better than the others, with some subjects preferring it over commercial radio. Crucially, subjects expressed a strong belief that these systems could be improved to fully meet their needs, rating them more positively in this regard than existing technologies. Subjects indicated a willingness to pay an average one-time fee of $117 for a system that completely met their needs, though 15–20% would pay nothing. The study concludes that while current implementations lacked reliability, the concept of personalized, route-specific "push" systems holds significant value as a complement to commercial radio. Drivers desire timely, customized information that suggests alternate routes and reduces uncertainty, features that generic broadcast systems cannot adequately provide. The authors suggest that an ideal system would combine interrupt capabilities with on-demand availability. Although none of the tested systems fully met these criteria, RDS/SCA appeared most adaptable. The findings imply that future traffic information systems must prioritize reliability and personalization to gain driver acceptance and effectively influence travel behavior.

Key finding

Drivers perceived the tested DIRECT traffic information systems as significantly less reliable than commercial radio, yet rated them as more route-specific and available on demand, with RDS/SCA receiving the most favorable subjective evaluations among the new systems.

Methodology

naturalistic

Sample size: 174

Provenance

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

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Information type

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• Applied Guidance: countermeasure evaluation
• Empirical Findings: self report data, observational prevalence