HerRestroom is a virtual queue management app designed to tackle long queues at women’s public washrooms. Using real-time occupancy data, GPS navigation, and smart notifications, it helps users minimise wait times and physical discomfort.
This is not merely a personal inconvenience — it is a systemic problem caused by public infrastructure that neglects gender-specific needs.
Women consistently face longer wait times at public washrooms than men. Menstruation requires changing sanitary products, clothing adjustments take more time, and higher hygiene standards mean stalls take longer to turn over. Compounding these factors, most public facilities provide fewer cubicles for women than for men.
The consequences extend beyond inconvenience — prolonged standing causes physical discomfort, particularly for the elderly, pregnant women, and those with medical conditions. Our research interviewed four women aged 16 to 76, spanning students, working professionals, homemakers, and retirees.
Research shows women are 34 times more likely to queue for a public washroom than men. Average wait times reach 10–15 minutes during peak hours in malls, and can exceed 30 minutes at concerts or tourist attractions.
Using Contextual Inquiry methodology, we gained in-depth understanding of how women of different age groups behave and feel when facing long washroom queues.
“If the queue is too long, I find another washroom, or I use one early even when I don’t really need to — just to avoid being caught in an urgent situation later.”
“If the queue is too long, I’d rather go to another floor. Dirty toilets also discourage people from using them, which actually makes the queue longer.”
“At K-pop concerts, everyone rushes to the washroom during VCR breaks. Some fans walk far to find another washroom rather than wait in the long line.”
“At West Kowloon Cultural District, the queue stretched so far. I waited 15 minutes feeling extremely urgent. I was so rushed I forgot to clean the seat — I felt embarrassed.”
The app displays current cubicle availability and queue length, allowing users to decide whether to join the queue or seek an alternative before approaching. This directly addresses the misleading “door closed but no one inside” problem observed in our user studies.
Based on the user’s current location, the app displays nearby washrooms on a map with their respective wait times and occupancy status, enabling quick, informed decisions and eliminating the need to wander around searching.
Users join a virtual queue remotely and are free to shop or rest while waiting. The system sends a push notification 3–5 minutes before their turn, transforming an uncomfortable physical wait into a flexible, comfortable experience.
Building on G1 findings, we created Personas, Storyboards, low-fidelity wireframes and individual hi-fi prototypes before consolidating into a final group interactive prototype.
Interactive Prototype
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to explore the full user flow
Three scenario storyboards illustrate how each core task addresses a real user need.
Actor: Ada Cheung, 65, uses a cane
Ada feels the need to use the washroom while shopping but doesn’t know where the nearest one is. She opens the app, which pinpoints her location on the floor map and highlights the nearest women’s washroom — just around the corner. She arrives in under two minutes with no physical strain.
Actor: Lisa, busy working professional
Lisa arrives at the washroom on a tight schedule and sees a long queue. She checks the digital display via the app: “Available: FULL — Estimated Time: 2 mins.” The clear estimate gives her confidence to stay and queue, and she makes it back to her meeting on time.
Actor: Ada Cheung, 65, uses a cane
Ada proactively taps “Remind Me Later” and sets a threshold of fewer than 3 people. She shops comfortably for 30 minutes until her phone buzzes: “Queue at Wing A has dropped below 3 — head over now!” She walks over calmly and uses the washroom with no stress or physical strain.
Each member independently created 2 low-fidelity wireframes (10 total) and then a personal hi-fi prototype covering the 3 key tasks, evaluated with 1–2 target users. Click any card to view.
Multiple approaches to destination selection; distance markers and navigation paths provided a solid starting point.
Inconsistent layouts; cluttered screens; no real-time feedback at low-fi stage; unclear visual hierarchy.
Merge best elements into a clean map view with distance markers and a prominent “Find Nearest” button; introduce unified, simple layout.
Advanced features explored: queue tracking, reminders, cancel queue — offering flexibility in notifying users.
Inconsistent UI layouts; unclear differentiation between active and completed queues; limited customisation for reminders.
Standardise layout; add threshold notification settings; clarify queue status indicators with consistent design.
Clear display of occupancy, wait times, queue lengths; actionable “Join Queue” button; real-time ticket progress.
Fragmented flow between list and detail views; information overload; no filtering for accessibility or wait time preferences.
Unify views into a cohesive flow; add filtering options; prioritise nearest/least crowded washroom; enhance dynamic updates.
Across all individual reviews, users consistently struggled with three issues: understanding queue status and priorities, interpreting visual elements (map markers, colour meanings), and finding some features redundant under urgency. The group made the following consolidated changes:
We recruited 3 target users to conduct usability testing of the HerRestroom group prototype, collecting data across three ISO 9241-11 dimensions — effectiveness, efficiency, and satisfaction — to verify and refine the final design.
After evaluating the G2 prototypes with target users, five key issues drove the G3 redesign. Each card shows the user feedback that motivated the change and the resulting design decision.
Participants noted each team member’s prototype used a different colour palette, making the app feel inconsistent. P2: “The screens look like they’re from different apps.”
Adopted a unified pink (#F48FB1) + blue (#5C9EE8) colour system across all screens. Pink for interactive elements and CTAs; blue for map and status indicators.
Users navigated to the mall via the street map but were lost once inside. P3: “I found the mall, but once I’m inside I still don’t know which floor the toilet is on.”
Added an indoor floor plan view that activates when a mall is selected — showing corridors, lifts, and colour-coded washroom pins. Users can switch floors via a panel selector.
Users struggled to translate the 2D route line into real-world movement. P1: “I can see the line on the map, but when I look up I’m not sure which direction to walk.”
Introduced an optional AR mode: the phone camera overlays directional arrows, distance, and destination labels on the real-world view. Toggle between standard map and AR via a labelled button.
The G2 prototype launched directly into the map with no orientation. P2: “I wasn’t sure how to get back to the main page or switch to my queue status — it felt scattered.”
Added a home screen with quick-access cards (Find Washroom, My Queue, Profile) and a persistent 3-tab bottom navigation bar (Map | My Queue | Profile) across all main screens.
The G2 prototype felt like a feature demo rather than a complete app. P1: “There’s no login, no history, no settings. It doesn’t feel like a real app yet.”
Added a splash/loading screen, a login & sign-up screen, and a profile screen (notification preferences, saved washrooms, queue history) to create a complete, ecologically valid prototype.
Three female participants were recruited via convenience sampling, matching the primary user personas. All had prior experience with long public washroom queues.
Age 21 · Daily smartphone user · Attends concerts regularly · High tech proficiency
Age 29 · Frequent mall visitor · Time-conscious · High tech proficiency
Age 62 · iPhone user (WeChat & maps) · Low–Moderate tech proficiency
Scenario: You’re shopping at a busy mall and need the washroom. Open the app, find women’s washrooms on this floor, and tell me the queue length and estimated wait time for the closest one.
Scenario: The nearest washroom shows a 7-minute wait. Join its virtual queue and check your position and estimated turn time. Note whether you have time to grab a coffee nearby.
Scenario: You’re waiting elsewhere when the app sends a notification that you’re next. Check it, confirm “On My Way”, and describe what happens next.
Scenario: You accidentally joined the wrong floor’s queue. Switch to the correct washroom (Floor 3, accessible stall). Or, if you miss your turn notification, rejoin without losing too many positions.
Scenario: Imagine you’re at a concert with a short intermission. Repeat Tasks 1–2 in a stadium venue, then rate how the app helped or hindered your experience compared to standing in a physical queue.
| Task | P1 | P2 | P3 | Completion | Mean Time | Target | Met? |
|---|---|---|---|---|---|---|---|
| T1 — Check Queue Status | 100% | 100% | 50% | 83% | 22s | < 30s | ✓ |
| T2 — Join Virtual Queue | 100% | 100% | 100% | 100% | 38s | < 45s | ✓ |
| T3 — Respond to Notification | 100% | 100% | 100% | 100% | 14s | < 60s | ✓ |
| T4 — Error Recovery | 100% | 100% | 50% | 83% | 47s | ≥ 80% independent | ✓ |
| T5 — Concert Scenario | 100% | 100% | 50% | 83% | 55s | — | ✓ |
100% = completed without assistance | 50% = completed with errors or backtracking | 0% = failed / required moderator assist
P3 confused her own location pin with the washroom pin on both the street and indoor mall maps, causing hesitation and a 50% completion on Tasks 1 and 5.
P3 was unsure how to switch floors on the indoor mall map. She missed the floor selector panel on the right edge of the screen and needed a prompt.
Both P1 and P2 did not notice the AR mode button on first use. P2: “I didn’t realise there was an AR option — I thought it was just a normal map.”
Both P1 and P3 missed the “Notify when < N people” radio buttons on the Remind Me screen on first interaction.
All three participants responded positively to the unified colour scheme. P2: “It looks much more polished. The pink and blue feel consistent and feminine without being childish.”
All participants rated the indoor map as the most valuable new feature. P1: “Street maps are useless once you’re inside — now I can see exactly which corridor the toilet is in.”
All participants navigated between Map, My Queue, and Profile without assistance after the home screen was introduced. P2: “Now I can see everything is organised. Before I had to guess.”
Tasks 2 & 3 completed without any assistance by all three participants. P2: “I love that I can keep shopping and not stand there. The notification timing felt just right.”
An overview of the iterative design process across all four project milestones.
Identified “long queues at women’s washrooms” as the design problem. Defined target user groups and arranged initial user study appointments.
Conducted 4 contextual interviews, built an Affinity Diagram, defined 2 Personas and 3 key user tasks to guide the design process.
Completed Storyboards, 10 individual wireframes, personal high-fidelity prototypes and user reviews, culminating in a consolidated group interactive prototype.
Recruited 3+ users for usability testing, revised prototype based on findings, and completed the project portfolio and final presentation.
CS3189 User-centred Interaction Design · City University of Hong Kong · AY2025/26 Semester B