Do parking payment machines have to be so confusing?

When faced with a car park machine, Kevin Hallas of HSE’s Centre for Human and Organisational Performance, is convinced he’s not alone in the struggle to work out where to put the ticket, where the credit card goes, which screen to look at and how to get a receipt.

I travel a fair bit for work, so I park in lots of unfamiliar car parks. I don’t struggle to find them using a well-designed satnav app that seamlessly guides me to the entry barrier from hundreds of miles away.

It might take a few prods of the ticket dispenser to get me in, depending whether it has an actual button (big and green is great!) or some kind of touch-sensitive screen, or whether the ticket has already popped out whilst I was still hunting for a big green button.

Once inside, I don’t struggle as car parks are basically all the same, and I’ve learned how to reverse into a space quite successfully. It’s only when I come to pay at the machine on the way back to the car that I seem to lose the ability to comprehend anything.

Is that the slot for the ticket or my credit card? Both, maybe? Is that a token slot or is it for coins? [a queue is starting to form, come on, quickly…] Which screen am I following? Press here for a receipt – quickly though, it’s a time-limited offer! Where’s the receipt coming out? Take the ticket…

…If this isn’t you, perhaps you’ve stood in the queue wondering why the heck it takes other people so long to pay.

So what’s the problem? Well, the human interface on parking payment machines is generally awful! Firstly, they’re all different; there’s no convention. Secondly, there’s no logic – the sequence of tasks is not reflected in the layout. So you’ve been set up to fail from the start…

The benefits of user-centred design

We actually know a lot about human behaviour and how to design systems that are easy to use. For the parking machines, a good starting point would be to perform a link analysis: looking at every step that the user needs to complete, and getting them in the best sequence. You can then take this sequence and use it to inform the layout of the machine. The part of the machine that the user interacts with could be designed without needing to know anything about what goes on inside. Get the perfect easy-to-use layout, and then let the clever engineers make it work.

I suspect the reality is that the engineer dictates the layout on the outside, based on what is easiest to set up inside. Almost as an afterthought, someone then ‘designs’ the outside with all the key interaction points already fixed. All of the shortcomings this presents are then ‘overcome’ with various signs, symbols and instructions that ultimately conspire to baffle the user. A really well designed ticket machine would need no instructions, and people could use it really quickly.

We see the same issues when investigating workplace accidents. My colleague, Amy Jones, has spent a lot of time looking at entrapment accidents involving people in scissor lifts and cherry pickers (collectively referred to as mobile elevated work platforms (MEWPs)). A careful analysis of accident reports has shown a common theme of mis-operation of the controls, leading to unintended movements of the machine and resulting in the operator making unintended contact with something solid!

What does this have in common with the mundane car park ticket machine? Well, for those who don’t work with MEWPs, I can tell you that their controls lack consistency from one machine to the next and clarity in their labelling. Is training a practical safety measure for the risk when every MEWP is different? The accidents say it isn’t, the ergonomics say it isn’t and, in any case, how could you train people in the safe use of MEWPs when the user interface of each specific machine is designed so differently? Training has its place, but a good user-centred design would go a long way to making these machines less hazardous. The good news is that, having seen the light, manufacturers are now working towards better and more consistent controls.

It’s worth asking the question, the next time you come to review an incident or reported near miss at work, “was doing the right thing the easiest and most logical thing for those involved to do? Or – like so many of these blasted parking payment machines – are you relying on signs, instructions and training to compensate for an illogical design?

Want to share your thoughts or ask a question about user interface design, process design or ergonomics, and their impact on health and safety? Leave your comment below.

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