Development and Evaluation of an Age-Friendly Transportation Planning E-Tool: A Co-Designed Interface to Enhance User Experience by Addressing the Needs and Preferences of Older Adults (Preprint)

BACKGROUND Older adults often face challenges using digital transportation planning tools to engage in meaningful activities. Despite the growing demand for accessible and inclusive technologies, interfaces are often not tailored to the specific needs and preferences of older adults, making them difficult to use. Addressing this gap is essential to support the mobility and social participation of older adults in their communities. OBJECTIVE This study aimed to enhance older adults’ experience with a transportation planning e-tool – called Mobilainés – by co-designing its interface and evaluating its usability and user experience in line with their needs and preferences. METHODS Grounded in a participatory design approach, the study encompassed both development and evaluation phases, integrating qualitative and quantitative methods. In the development phase, heuristic evaluation of six existing transport planning tools (three websites and three mobile applications), along with the Mobilaînés mock-up, was performed to identify the percentage of compliance with age-friendly usability design principles and guidelines. Fourteen co-design workshops with the steering committee and research team informed persona development and core functionalities, while three workshops with older adults refined the mock-ups. For the evaluation phase, two laboratory usability tests (simulated context) and one in-field test (real-world context) were conducted with 5,7 and 4 older adults respectively. Data were collected using a combination of objective performance metrics recorded in real time by a computer and subjective user feedback, gathered using the System Usability Scale (SUS), the Unified Theory of Acceptance and Use of Technology (UTAUT) questionnaires, and focus group discussions. For the in-field testing, user experience data were obtained via the User Experience Questionnaire (UEQ) and semi-structured interviews. Quantitative data were analyzed descriptively, and qualitative data thematically. RESULTS The Mobilaînés mock-up interface demonstrated 67% compliance with the age-friendly usability design principles and guidelines, with overall compatibility increasing from 72% to 95% throughout the simulated and real-world context usability tests. Metrics revealed improved travel-planning performance: error rate dropped from 46% to 22%, task completion rose from 79.6% to 97%, with task duration remaining nearly stable. The SUS score improved from 54.6 (unacceptable) to 81.5 (very good) between tests, with UTAUT scores showing a similar pattern of improvement. UEQ and interviews from the in-field usability test revealed that participants found the e-tool reliable, easy to use, and accurate for travel planning, despite limitations such as the lack of real-time data. CONCLUSIONS By providing predictable, structured information and age-friendly features, the Mobilaînés e-tool enhance older adults’ experience through improved usability in lab tests and confidence in real-world contexts. Future research should explore collaborative and technological strategies to support its adoption and sustained use, particularly among older adults with limited digital literacy.