Identifying and Prioritizing Age-Friendly Design Principles and Guidelines for Developing Transportation Planning E-Tools: Scoping Review.

Background: Older adults often face mobility challenges and usability barriers when navigating transportation options due to age-related physical, cognitive, and sensory changes. While transportation planning e-tools can support their independence, most are not designed for their specific needs. There is a lack of comprehensive, age-friendly usability design principles tailored to this context. Objective: This study aims to identify, synthesize, and prioritize the most relevant age-friendly usability design principles and guidelines for developing transportation planning e-tools that are tailored to the needs of older adults. Methods: A scoping review was conducted following the Arksey and O'Malley methodological framework, enhanced by guidance from the Joanna Briggs Institute and reported according to the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews) standards. The literature search was performed across the following six scientific databases: MEDLINE (PubMed and National Center for Biotechnology Information), AgeLine (EBSCOhost), Cochrane Library (Wiley Online Library), Scopus (Elsevier), IEEE Xplore, and TRID (Transportation Research Board), and was supplemented by gray literature identified through Google Scholar and Google Search, covering the period from January 2013 to April 2025. To guide the analysis, 4 foundational usability frameworks by Nielsen; Shneiderman and Plaisant; Gerhardt-Powals; and Weinschenk and Barker were used to inductively derive generic principles that structured the classification of age-friendly guidelines. This process resulted in the organization of extracted guidelines into 10 core usability principles. The analytic hierarchy process was applied by a single expert to rank the principles based on expert pairwise comparisons and their frequency of reference in literature. Results: The study identified 31 relevant studies. From these, 500 age-friendly guidelines were refined into 68 actionable guidelines across 10 usability principles: visual clarity, structure and navigation, ease of use, information, minimizing memory load, feedback, accessibility, consistency, simplicity, and control. The analytic hierarchy process ranked visual clarity (36.4%), structure and navigation (22.1%), and ease of use (12.5%) as the top 3 age-friendly design priorities. Conclusions: This study offers an evidence-based foundation for developing transportation planning e-tools that promote older adults' autonomy and digital inclusion, with prioritized guidelines applicable to transportation planning e-tools and to the broader field of age-friendly digital design. Ongoing updates and active user involvement are essential to ensure their sustained usability and long-term relevance.