Alternate Interchange Signing Study for Indiana Highways

Chen, Stanley; Chen, Yaobin; Tian, Renran; Li, Lingxi; Liu, Donglin; Zhou, Jue; Shen, Dan · 2021 · ROSA P / Purdue University. Joint Transportation Research Program

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Summary

This study addresses the disconnect between standardized highway interchange signing designs and driver comprehension in Indiana. While current signage follows Federal Highway Administration standards, drivers frequently report confusion, leading to potential safety and efficiency issues. The research aimed to understand signing problems from the driver’s perspective and develop recommendations to improve interchange sign design, thereby enhancing traffic safety and operational efficiency. The researchers, affiliated with the Transportation and Autonomous Systems Institute at IUPUI and collaborating with the Indiana Department of Transportation (INDOT), conducted a multi-phase study. First, they cataloged over 300 interchanges in Indiana, documenting their types and associated signage using Google Street View. To identify problematic signs, the team designed an online survey distributed via email, social media, online newspapers, and a market research firm. The survey required participants to pinpoint confusing signs on a map, upload images, and describe the issues. Due to the complexity of the task and the COVID-19 pandemic, response rates were low; only 84 valid responses were collected, primarily through email distribution. Three researchers independently analyzed these cases, supplementing unclear responses with contextual data. The analysis revealed several key findings regarding driver behavior and sign effectiveness. Drivers typically lack knowledge of interchange types and prioritize knowing which lanes to occupy well in advance of typical signing locations. Drivers expressed a strong preference for signs that minimize cognitive work, as complex information creates uncertainty and delays decision-making. The study found that information needs vary significantly among drivers; a sign providing optimal information for one user may cause confusion or information overload for another. Additionally, drivers familiar with an area were sometimes confused when sign information contradicted their existing knowledge of local geometry or directionality. The researchers categorized these issues into 19 specific problem types, such as inconsistent lane markings, confusing temporary signs, and signs located at geometrically challenging points like curves or close consecutive exits. The significance of this work lies in its actionable recommendations for INDOT. The study provided specific remedies for sign layout, location, and type for each identified problem case. INDOT has already modified some sign layouts based on these findings and plans to integrate these lessons into future design standards and the Indiana Design Manual. By aligning signing design more closely with driver expectations and cognitive limitations, the research aims to reduce confusion and improve the overall safety and efficiency of Indiana’s highway network.

Key finding

Drivers prioritize lane assignment information and find signs confusing when they require excessive cognitive processing or contradict local knowledge, highlighting the need for tailored signing designs.

Methodology

survey

Sample size: 84

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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• signage environment
• rail grade crossings