Physical UX: Are 2 lanes better for fast paced restaurants?

Physical UX: using 2 drive thru lanes

So I think we needed to have something about Physical UX and how installation design will improve user experience. In this case, I’ll demonstrate this with mathematical theory (remember: UX is a science!). There’s a bit of Urban UX involved, hope you like it.

A question about installation design

The original question made by user pacoverflow was about restaurants (In this specific case McDonald’s, don’t miss the article we just had last week).

The original question featured photos of a double drive thru restaurant and wondered about the benefit of having two drive thru lanes instead of one.

This specific question may not be the best example of Physycal UX (we’ll have a lot about that soon). However, it’s a pretty good example of how a relatively simple problem may cause a lot of bigger problems. And how scientific research can solve these problems using data-driven design.

Physical UX problems solved

Problem 1: Time

The first reason to have a double drive thru installation design is that it saves time. While this is kind of obvious, there’s a very extense (and dense) corpus of knowledge and theory behind this reasoning, with many mathematical formulas. This particular problem is based on Theory of Constraints, a principle from management disciplines

The theory of constraints (TOC) is a management paradigm that views any manageable system as being limited in achieving more of its goals by a very small number of constraints. There is always at least one constraint, and TOC uses a focusing process to identify the constraint and restructure the rest of the organization around it. TOC adopts the common idiom “a chain is no stronger than its weakest link”. This means that processes, organizations, etc., are vulnerable because the weakest person or part can always damage or break them or at least adversely affect the outcome.

Theory of Constraints

In other words: we identify a problem, a “weakest” link in a production line, and try to find a way to solve that problem before it breaks the whole production line.

Physical UX: Installation Design with 2 drive thru lanes
Installation Design of 2 lanes working normally

Let’s say we have 2 rows of 4 cars and it takes 3 minutes to each car to make an order, plus 1 minute to pay. Since they’re taking orders in parallel, it will take 12 minutes to each row to go through, plus 8 minutes for all cars to pay.


That totals 20 minutes.

Urban UX design of one lane
In this case, we have only one service lane, which leads to delays. Therefore, by Theory of Constraints we’re creating the weakest link in the chain.

Now, think about the same scenario, only with just one drive-thru:


it will take 32 minutes.

So, with just a simple operation we can do with just paper and a pencil (in general you don’t need much more than that for most UX tasks), we can identify the issue and provide a simple solution. Which, in this case, is the double drive thru.

User Experience

Same case, only with just one drive thru.

The first 3-4 cars will just wait patiently. The other cars will grow impatient, and maybe even try to get out and go to another restaurant, causing trouble to the cars behind or getting stuck in the middle. Needless to say the amount of frustration will skyrocket.

Emotional Design: Distress kid crying in car
Emotional Design is one of the main areas of User Experience. Emotions can be good, bad or neutral. What kind of emotions do you think this kid and his parents are experiencing?

If you want more drama, try to picture this with 3 kids yelling and you’ll get the perfect nightmare (and obviously, this user will never get back, granted).

Avoid friction

Same situation.

Now you come with your car and see a long line of cars that gets to the road. Being smart, you say to yourself:

is the time I will spend here worth it?

Quite probably not, so you move out to another place.

Physical UX grpah showing discontent rate between customers
Physycal UX also considers discontent rate. A proper CX strategy should consider this data for any type of development

Maximize costs/benefits

Consider the cases mentioned in my first point. Now let’s say you need 10 cars to pay your employees, and you have only one employee per station (taking orders and cashier). For the purpose of this example, you work at full capacity 8 hours.

So, with 2 drive lanes you have 3 employees, therefore you need 30 cars to pay the costs.

As I mentioned before, it will take a total of 4 minutes to each car. But since they go in parallel, it will take 75 minutes to pay the costs, with an average of 2.5 minutes per car.

Then you’ll have 405 minutes of remaining time, or 162 cars

(405 minutes / 2.5 minutes = 162 cars )

One lane case: you need 2 employees, hence 20 cars. It will take them 100 minutes (20 x 4 minutes) and leave 380 minutes of remaining time.

Now the numbers are like this:

380/4 = 92

So, you saved a bit in employees wages, but your income will fall drastically, almost to half.

However, this is not a “one size fits all” formula. Please note that if you don’t have enough traction (customers) having only one lane will probably be the best idea


Physical UX: Are 2 lanes better for fast paced restaurants? 1

Let’s say you’ve a busy restaurant.

Then, oh catastrophe! something happens. After all…

If one thing goes wrong, everything else will, and at the same time

Drucker’s Law, Peter Drucker

Let’s say the ordering computer goes kaput. Or your employee fails to show up. Or something happens that makes you close one of the lanes (for example, public services installation, or some kind of structural problem)

So you lose sales until you fix the issue. By having another lane, you will prevent the chances of losses by (literally) 50%

Conclusion: Why is Physical UX so important?

Proper installation design based on Physical UX (and Urban UX whenever needed) is a sure path to create succesful user experiences that will pay by themselves.

Any investment in Physical UX will yield at least 10x its value (in absolute monetary terms). But most important: it will improve your brand perception, and create safe and comfortable spaces for customers as well as employees.

The use of scientific method to extract data and interpolate results is a tool that helps any business manager, and Physical UX makes extensive use of that tool and its methodologies.

In short: It’s so important because it’s only advantages without any downside.

Installation Design, Urban UX and Physical UX resources

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