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Analyze subway turnstiles with Professor D. Jackson’s design criteria

Posted on July 22, 2020

Human-Computer Interaction for User Experience Design


In this unit, you learned about the criteria that underpin interaction design, namely: ease of use, pleasantness, safety, security, and accessibility. To further engage with these ideas, watch Professor Daniel Jackson  present subway turnstiles as an example where these five criteria can be applied.

After watching the video, think about the user interaction in the example in this video, and share your thoughts with your small group on where you can apply the five interaction criteria to this user interaction.


1. Ease of use

Subway turnstiles are quite easy to use, for the most part.

1.1 Learnability

The rotating turnstiles usually only offer only one motion direction at a time. When users try to go in the wrong direction, they quickly face a locked turnstile and understand either they cannot go in that direction, or something is needed to unlock the turnstile.

That’s usually when the confusion sets in; the surroundings of the device are not always clear as to what the user can do: should users look on the left, the right, swipe a card, enter a ticket, and if so, should they pick it up or not on the other side?

That side is lacking learnability and requires users to look around and read instructions or be instructed by someone. There is a risk of information overload (many signs and marketing adverts competing for users’ attention) or it may not be possible for users to rely on external people for help (person not present, language difference, extreme anxiety, etc.)

1.2 Efficiency

Once that potential confusion is cleared, users can be quite efficient at swiping and passing through, at the same speed they are walking.

A bottleneck could be created when novice users and experienced users share the same space.

1.3 Error tolerance

Because of minor differences in implementation (as discussed in the point 1.1 above), turnstiles are designed to cause errors first so that users can learn how to use them. The first interaction with the object is restriction or frustration.

They do work well as an error: many people abuse turnstiles’ unique direction by rotating them in the opposite direction, thus bypassing their restrictive nature.

2. Pleasantness

The slick surface of the pegs makes the transition smooth helps not making using turnstiles a worse experience.

The devices are not particularly pleasant or unpleasant to use. They are a minor hindrance when going through.

They could be designed better though. Designer and activist Aral Balkan once mentioned in a talk that people going through the subway do not wish to spend time with the devices that allow them to navigate in the subway (turnstiles, ticket booths, etc.), but rather that they wish to go some place. Any hindrance along the way makes the experience slightly more tedious.

In a post-coronavirus world, objects that are repeatedly touched by strangers might be much less pleasant to use.

3. Safety

Subway turnstiles do not seem to pose a safety risk when using them.

However, depending on their design, they could be problematic in the case of a crowd needing to rush out of a place where turnstiles restrict movement.

4. Security

Turnstiles are placed to ensure that users pay a fare before using a service (although cities like Brussels work differently).

As explained above in point 1.3, abusing the turnstile allow people to go through without paying. The financial security of the subway system is what would be hurt in that situation.

5. Accessibility

These objects are not made with accessibility in mind, in fact they are designed only for the fully functional fit people of the average height:

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