PT Guide

Overview

PT Guide is an iPhone app I designed and developed as the final project of my vocational training as a software developer. It guides blind and visually impaired users through public transit journeys using location tracking and VoiceOver, providing audio cues before stops so riders know when to get off.

At the time of completion, it was, to my knowledge, the only app of its kind specifically designed for blind users.

The starting point was a news article about a blind person's experience using an iPhone. What struck me was not just the accessibility challenge but the practical transit problem: stop announcements in Hamburg buses and trains were unreliable or absent, and no app was filling that gap for someone who couldn't glance at a display.

Designing Without a Screen

The fundamental challenge wasn't technical. It was conceptual: most interface design assumes a sighted user who can take in a whole screen at once, navigate spatially, and scan for what's relevant. VoiceOver users experience interfaces linearly, one element at a time, in the order they appear in the accessibility tree. Designing for that is a different discipline.

To understand what that actually meant in practice, I started with user research. Interviews with blind iPhone users revealed how they interact with VoiceOver: the navigation patterns, the mental models, the things that trip them up. A standard iOS layout that works fine visually can be laborious or confusing to navigate by touch and audio if the element order doesn't match the logical flow of a task.

From this, I developed an audio-first design approach:

• Every non-text element (images, icons, controls) was annotated with an alternative description meaningful in context, not just technically present.
• Screen layouts were structured for linear, sequential discovery rather than spatial arrangement, because blind users cannot take in a bird's-eye view of a page.
• Wireframes included explicit notations of VoiceOver interaction flows, not just visual layouts.

From Prototype to Blind Users and Back

All key development milestones were tested with blind iPhone users, not just by me using VoiceOver. That distinction matters: someone who can see will always have a different relationship to an audio interface than someone for whom it's the primary input. The feedback from these sessions shaped the interaction model repeatedly: adjusting element ordering, rewriting labels that made sense visually but were ambiguous when read aloud, and tuning audio timing for noisy transit environments.

The final version was also fully tested by blind users before release.

What the App Does

Riders enter a destination stop, and the app tracks their location during the journey. As the bus or train approaches the destination, the app provides audio notifications, accounting for the time needed to stand up and move to the exit. Frequently used stops can be saved as favourites. Throughout the journey, the app provides live distance updates to the destination.

Every interaction is accessible by touch and gesture through VoiceOver, with no visual elements required to operate the app.

Outcome

PT Guide was, at the time of release, one of very few apps designed specifically for blind users and the only transit navigation app of its kind. The co-design process with blind participants validated the approach and produced a fundamentally different result than designing for sighted users and retrofitting accessibility afterward.

The project shaped my understanding of accessibility as a design discipline, not a checklist. The principles I developed: designing for linear navigation, meaningful rather than decorative labels, testing with the actual target users, continue to inform how I approach accessibility today, including in more recent work like ZigHaven's full VoiceOver implementation.

The app was discontinued in 2015 due to time constraints.