Case Study — Ridlr / Mumbai Metro One

An interface fast enough to keep a rush-hour queue moving.

Client Reliance Mumbai Metro One
Scope Counter-side ticketing system, end to end
Role Lead — Product Strategy & UI/UX — Pritam
Year 2019 – 2020
01 — The Brief

Reliance Mumbai Metro One

Public Transit · Metro Rail
Mumbai, India
Via Ridlr — Birds Eye Systems
——
Counter ticketing system

Mumbai Metro One runs the 11.4-km Versova–Andheri–Ghatkopar corridor — twelve stations, over four lakh riders a day. Every single-journey rider bought a plastic token at the counter, tapped through the gate, and returned it on exit, where it was collected, sorted, and reissued the next morning.

Metro One moved single-journey ticketing to a printed paper QR code: faster to issue at the counter, simpler to operate, and carrying a surface that could later hold advertising. Ridlr — already running mobile QR ticketing through its app — was brought in to build the counter-side system.

The brief was the interface itself — the screen a station clerk would use on a new Sunmi T2 Mini POS terminal, thousands of times a shift, with the rush-hour queue waiting behind every transaction.

02 — What We Found
A counter clerk never reads the screen. They glance, tap, and move on — four thousand times a shift.

We spent two weeks at the busiest counters — Ghatkopar, Andheri — watching the transaction that actually mattered: the seconds between a rider naming a destination and holding something to enter with. That gap was the whole job.

Staff process three to four thousand transactions a shift, on muscle memory built over years. At Ghatkopar, more than sixty percent of tickets sold go to just three destinations — clerks know those fares cold and issue them almost without looking down.

So the real design metric was tap-count under pressure — the number of taps between a spoken destination and a printed ticket — not how modern the screen looked. An interface that kept pace with a clerk's hands would keep the queue moving. One that asked them to search or scroll would hold it up.

03 — Our Approach
Design for the clerk's hands, not the commuter's eyes.
  • 01 A single-task instrument. Hear a destination, tap it, print the ticket. Three actions, one screen — no menus or settings standing between the clerk and the next rider.
  • 02 Frequency-first layout. The most-issued destinations take the largest touch targets, and each station's device is ordered by its own patterns. A Ghatkopar clerk sees Andheri and D.N. Nagar first; a Versova clerk sees Andheri and Ghatkopar. The device adapts to where it sits.
  • 03 Tap-count as the deciding metric. Every layout was judged by one number: taps to ticket. The chosen design reaches a two-tap transaction for the top sixty percent of journeys and three taps for the rest. No flow runs longer.
  • 04 Tested at the counter. Prototypes were put in front of real clerks during off-peak hours, at the actual counter. Button sizes, spacing, and label density were tuned to observed tap accuracy.
04 — The Work
The Counter Interface

An 11.6-inch screen that does one thing well.

The Sunmi T2 Mini pairs an Android touchscreen with a built-in thermal printer — a compact, capable canvas. The final screen gives the clerk a grid of destination buttons ordered by frequency, a fare confirmation, and a print trigger. Nothing else competes for the glance.

  • Frequency-first grid The destinations a station issues most often hold the largest, nearest buttons. A clerk's common transactions land where their hands already expect them.
  • One screen, three actions Tap the destination, confirm the fare, print. The whole transaction lives on a single view — no navigation during the moment that counts.
  • Plain by design High-contrast type on a light ground. No icons or branding on the transaction screen — every pixel earns its place at the speed of a glance.
[ Screenshot — Sunmi T2 Mini ticketing screen, frequency-ordered destination grid ]

The counter interface — representational

Paper QR Ticket

The thermal printer produces a small paper ticket carrying a QR code, journey details, fare, and a validity window. The rider taps the QR at the gate on entry and inserts the paper on exit — a single, disposable artifact that the existing AFC infrastructure reads without change.

Generation, print, and gate scan were designed as one reliable loop, coordinated with the backend and hardware teams so the ticket worked the moment it left the printer.

[ Photo — printed paper QR ticket with journey, fare, and validity window ]

The printed ticket — QR, journey, fare, validity

05 — The Result
12
Stations live
across the corridor
4L+
Daily riders
at peak ridership
2×
Faster than
token issuance

The paper QR system went live across all twelve stations in early 2020, running at twice the speed of token issuance. Clerks adapted within days — the frequency-first layout put their most common transactions exactly where their hands already reached.

Busier stations ran up to twenty-five machines; smaller ones operated on a single device. Mumbai Metro One became the first public transport system in the city to issue entirely on paper QR tickets, with the printed surface opening a path to advertising the token never offered.

When the interface is right, the clerk thinks about the next person in line — not the screen. That's the whole design, and it lets four thousand people get home a little faster.

Pritam · 1 Less Design

← Back to Work Good design is as little design as possible — D.R.