Friday, February 1, 2008

Interactive Design: A Case Study Part 1 of 3

New York's MetroCard Vending Machine (MVM)
MetroCard Vending Machine

This post is part of a series exploring interactive design in an everyday object, the MetroCard Vending Machine. Please click below to read further:

Part 2
Part 3

New York’s MetroCard Vending Machine (MVM), created by Antenna Design, was planned with the diverse needs of millions of daily transportation users in mind. The first vending machine that is compliant with the Americans with Disabilities Act, it allows access to users who are blind, deaf, short, or wheelchair bound. Additionally, the MVM can present up to six languages from a library of seventeen; the languages are dependant on the ethnic groups in the neighborhood. For instance, Chinese is an option in Manhattan’s Chinatown and Polish is available in Greenpoint, Brooklyn.

The design of the MVM must be flexible to adjust to fare changes with minimum or no reprogramming and to have its use extended to all New York rail systems, including the Long Island and Metronorth railroads, in addition to Westchester County bus systems, which require a different type of MetroCard. Additionally, its sturdy design protects against theft or vandalism, with a stainless steel and ceramic body with is hard to scratch and easy to clean. Its modules are also color coded in primary colors, which makes it look like an arcade game.

The following is a sample transaction demonstrating how an MVM works. Each number represents a different screen with the options available in parenthesis. Bracketed items are MVM feedback.

1. Touch start to begin
2. Which language? (English, Espanol, Italiano, Deutsch)
3. Please select MetroCard type (Fast Metrocard $20, MetroCard, SingleRide)
4. [You have selected MetroCard]
Please select transaction (Add Value to your card, Get New card, Trade in cards)
5. [You have selected New MetroCard]
What amount do you want? ($4.00, $8.00, $20.00, $40.00, $80.00, more options)
6. [New MetroCard]
[You have selected $8.00]
How do you want to pay? (Cash, ATM card, Credit card)
7. [New MetroCard, $8.00]
[Green arrow points to money slot]
Please pay $8.00
8. [You now have a $8.00 MetroCard]
[Orange arrow points to MetroCard slot]
Please take MetroCard
9. Do you want a receipt? (Yes, No)
10. [Red arrow points to receipt slot]
Take your receipt
11. Thank you

The MVM was designed to offer maximum efficiency despite its separate technologies. For example, there are two dispensers because MetroCards are plastic and SingleRide cards are paper. There are also two keyboards: a physical one for ATM PINs and a virtual one for selecting the amount of money to put on the MetroCard. Ideally, there should be a single dispenser and a keyboard; however, some redundancy was unavoidable.

Although the external design of the MVM is commendable, the user interface is a hierarchical menu of mutually exclusive choices, which some users find difficult to use. Each module of the MVM’s user interface is a distinct color to make it intuitive as to which module does what, but many users still have to guess what the machine wants them to do next. Color-coded arrows point to where the next transaction happens. For instance, when the machine wants you to insert money, a green arrow points to the money slot. Since there is no easy way of lowering the number of interactions needed to get a MetroCard, the modules could have been arranged sequentially. A MVM consists of a screen, a scrolling display, an ATM PIN keyboard, and separate slots for MetroCards, credit/ATM cards, dollar bills, coins, and receipts, all of which can be overwhelming to the user.

To use the machine, the user has to touch a start button on the screen. For many users, this is a gratuitous step. However, for the uninitiated, touching the Start button is natural mapping, guiding the user away from the physical buttons and focuses their attention on the screen.

The second step is to select a language. Many New Yorkers believe English should be the default. However, since different neighborhoods have different language selections, English may not be the predominant language of the area. Alternatively, the language choice could have been integrated into the Start step by showing “Start” in different languages. This would create six Start buttons on the first screen, which could easily more problematic than a step for language selection. Although there is no easy answer, the text needed for a transaction is so limited that an experienced user could probably purchase a MetroCard in an unfamiliar language.

The user interface would most benefit from being more error proof. Each screen has a white “Go Back” and a red “Cancel” button on the bottom of the screen. However, there are times in which Cancel brings the user back to the Start screen. This is not helpful because in most cases, the user still wants to buy a card, but chose something that canceled it instead. For example, if a user wants to refill a card, which has been damaged, the screen returns to the Start screen rather than another, more helpful screen in the hierarchy.

A goal of user-centered design is to determine the right visual priority of the various functions offered by a particular interface. Obviously, not every button can be presented with the same degree of prominence and it is always hard to decide which functions should be front and center and which can be relegated to a less obvious placement. The MVMs make it easy to add fixed denominations to the card, but the “other amounts” button is easily missed by frequent users whose regular, ingrained interaction routine does not include this function. In other words, it is a function that a user would not notice unless he needed it.

From browsing several New York-centric sites and talking to people who use the MetroCard daily, the problem lies in offering faster service for everyday riders. They would probably prefer a more shallow hierarchy of options. For instance, when they want to refill a card, they could simply place the card in the slot, and the machine would assume a work flow based on reading the card and giving the user appropriate choices. The MVM was designed for all users—life-long New Yorkers, new immigrants, tourists—so the hierarchy is mutually exclusive choices is the best design choice.

1 comment:

eclipse said...

Very thoughtful article. Thanks for sharing.