Constraint Driven Design of Mass Transit Station Kiosk’s Case Study
Achieving Lean UX by implementing Usability Testing that avoids unnecessary hypothetical User Flow Documentation.
Imagine we’re designing a kiosk at a transit stop (e.g. a Metro Station). Its purpose is to let regular commuters refill their transit cards with cash.
Constraints
- There are four push buttons and four LEDs beside each button.
- There’s a card reader, bill acceptor, and dollar-coin return.
- The max amount allowed on a card is $50.
The machine is right next to a station agent, who can help with anything.
Expectation
Imagine the key tasks performed by a typical user and support each task through action-feedback loops.
Solution
We need to Implement Design Centric Iterative Product Development Process to come up with a Minimal Viable Product (MVP).
Subway Card Property
Generally, Subway Cards have a wide field of contact. It means a User can keep the Card inside the Wallet and touch the access point with the wallet to complete the transaction.
Debit cards and Credit cards have a narrow magnetic strip. It could be unveiled during Covert Observation, a type of Observational UX Research. Due to the narrow magnetic strip, users make mistakes frequently identifying right side up. Some machines have the slot to swipe and others have the slot to insert. Such situations can be avoided by using the wide field of subway cards effectively.
A flat square slot could be designed to place the card on top of it, any side up and any rotation. It could be mentioned in the slot “Place Card Here”.
Subway Kiosk Limitation
As described in the problem statement, the Kiosk is not equipped with a digital touch screen. It is having Human Machine Interface with some buttons and LED lights for feedback.
To know about Subway Recharge Malpractice please Click Here.
Ideal Hypothetical Task Flow
We must include only the minimal number of interactions required between the User & Kiosk to accomplish the MVP. This limits the chances of User Error too.
The above image of the Transit Card Kiosk given in the problem statement doesn’t have a number pad. Although, we do have to add an Analog Display to show the card’s balance. We can make it an automated card-reading machine and get rid of the 4 buttons as described in the problem statement. We also need to include 6 LED Lights and reposition them for proper feedback to the User, at each step.
The Digital Display will have “Recharge Kiosk” written to indicate that the machine is alive. A user can look at the machine from a considerable distance to identify if the machine is alive. If the machine is dead, the Digital Display will be turned off. If the machine is faulty, the Digital Display will show dashes.
The card will be read immediately after it is placed on top of the slot. The Balance will appear on the Digital Display and the LED above the “Place the Card on the Slot” will glow, indicating to the user that the card is active. The Balance will continue to appear as long the card is placed in the slot.
Next, after a 1-second deliberate delay, the LED above the “Insert Bill” will glow to reinforce the notion of a step-by-step sequence being followed by the User. Along with the LED, a false auditory signal of the roller can be heard (in the case of a modern quiet roller). The false auditory signal is coming from a standalone audio device. This will indicate to the User that the “Bill Acceptor” machine is now ready to accept the bills. The bills will be inserted one by one into the machine. The top-up will be added and the whole amount will update on the Analog Display. The machine will return the bill with a beep from the Insert Bill slot in any of the following cases. The standalone audio device will be used to produce the beep.
- The machine runs out of change.
- The bill is faulty.
- The amount can’t be loaded on the card due to a network issue.
- Max amount of 50$ is reached.
The LED above “Collect Change” will glow & dispense the change, once the Max amount of 50$ is reached. Simultaneously, the Digital Display will show Max Limit blinking beside 50$, suggesting to the user that Max Limit has been reached. This will complete the transaction and User Feedback Loop.
Ideal Hypothetical User Flow
Out of the many hypothetical scenarios, only one hypothetical ideal User Flow has been explained below.
You will soon find that a simple Task Flow has grown into a complex User Flow in no time, lead to Analysis Paralysis. Thus, one of the prominent things to do is to put the Kiosk in the actual environment to collect User’s Behavioural Usability Data and improve the Human Machine Interface Design iteratively.
Frequent Usability Testing cuts down the documentation for listing down all the unnecessary Opinionated steps of User Flow and help the team to concentrate on actual Behavioural Error of the User. Usability Testing makes the Designing Process Lean, Data Driven & Reliable.
The User’s Ethnicity is Indian. The average height of an Indian is 5 Feet 4.9 Inches as shown in Google. The Machine height has been kept at 5 feet to an average Indian eye level. The attributes covered in the User Flow are User Position (arbitrary), User’s Posture, Expected User’s Vision Focus, User Peripheral Vision, Expected User Hearing, and Expected User’s Action by Hand & Machine Feedback.
The Kiosk is not Special Need User-Friendly yet. The Kiosk needs to be tested for illiterates too.
