Choosing queues to minimize wait time

An article in the New York Times (September 7,2016) titled “How to pick the Fastest Line at the Supermarket” describes how choosing a line with one person with 100 items may be faster than a line with four people with 20 items each, with the former taking six minutes and the later taking seven minutes on average. The main issue, the article claims, is the setup time per customer – the time to say hello, pay for the purchase and say goodbye.  Given the estimated 37 billion hours spent by US customers in line each year, these details can improve service time.  But the article also claims that estimation of waiting time is a mental calculation with customers overestimating their wait times by 36%. How should service times design their architecture to influence both the actual time and perceived time ? How can service systems decrease setup time for queues, thus increasing productivity, while maintaining customer service perceptions ?

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24 Responses to Choosing queues to minimize wait time

  1. Kyle Harshbarger says:

    This is the second blog I’ve seen write about this article. The author also mistakenly thinks a customer has the choice between a “serpentine” line and single server queues (this choice is normally made by the business owner)

    I’m not sure the author found a ton of new info since Apu told us how to find the shortest wait time on The Simpsons 20 years ago…

    “Apu and Marge wait at the back of the long line in the express lane.

    Apu: Mrs. Simpson, the express line is the fastest line not always.
    That old man up front, he is starved for attention. He will talk
    the cashier’s head off.
    Abe: {Ah, there’s an interesting story behind this nickel. In 1957, I
    remember it was, I got up in the morning and made myself a piece of
    toast. I set the toaster to three — medium brown.}
    — Then he tied an onion to his belt, “Homer and Apu”

    Apu: Let’s go to…that line.
    Marge: But that’s the longest.
    Apu: Yes, but look: all pathetic single men. Only cash, no chitchat.”

  2. Sarah Rosnick says:

    This is quite possibly my favorite blog so far in the IMM program. In my mind, the most obvious answer is the development of the self-checkout lines. They are absolutely slower than a normal cashier handling the transactions, but the immersive type experience puts the burden entirely on the customer. They don’t have to greet the machine, there’s no need to tell it to have a good day, or to provide some sort of physical gesture to suggest warmth and appreciation. It gives the customer the perfect impression of control and speed.
    If we’re forced to accept a human is going to run this, then we find ways to distract the customer that’s waiting in line. Rudimentary ways to achieve this previously were with candy and magazines at the line. Now, we see things like commercials playing at gas stations while a car is fueling up. It gives a customer a chance to be distracted, provides name brands with a chance to influence and occupy the consumer’s attention, and ultimately gives many a better experience at the pump where they’re not staring impatiently at the numbers to roll over.
    In many cases, we thought we’d see a faster transition time in lines from the days when people would write checks since they would be limited to cash and cards. Surprisingly cash payments and making change is quite time consuming. I might set up specialty times that were card-only lines and I’d mandate that the cashier only begin conversation with the customer once they’ve swiped the first time. Additionally, I frequently find myself waiting for cashiers to approve whatever form of payment I’d like to employ…staring at a message on the card reader which tells me I’m waiting on the cashier. Much like the gas pump, I don’t really need to tell the cashier if i’m paying debit or credit. I should just be able to tap a button and move entire experience along before they’re through ringing up my groceries.

    • Jordan McCroskey says:

      You don’t talk to a self checkout machine? I find myself swearing at them as they don’t scan or the machine tells me to put the item in the bag that I already put it in the bag.

    • D. Zekveld says:

      I agree that the self check out ‘admin’ time is probably higher than a human cashier, but the benefit to the self checkout is that there is usually one line feeding to multiple machines. So while Jordan is swearing at the machine and trying to get the item out and then back into the bag, 3 other more tech savy millenials have passed through the other checkout which keeps the flow moving on the main line.

  3. Freddy Horn says:

    Obviously, some simple distractions such as implementing tv screens would help to reduce the perceived waiting time. Elevators also often have mirrors for the same reason, even though I doubt that they will have the same effect in a supermarket. People would probably be more hesitant to look at themselves with other customers standing around. A way to reduce actual waiting time would be to give shoppers mobile payment systems or use payment apps. For instance, a few years ago, the Italian super market chain Esselunga tested a system where customers were given mobile scanners with integrated credit card payment systems. The shoppers who chose to use this system had to put their credit cards in the scanners, scan the products that they wanted to buy, and confirm the payment at the checkout, which was just a stand where they returned their scanners. I tried it out myself and really liked it. The main concern was that this system would make it easier for people to steal. I wonder if they kept it or developed it further. I have not seen it anywhere else since.

  4. Kim Coldiron says:

    I am in complete agreement with Sarah on the self-checkout lines. So obvious, however, we are already seeing many of these removed from retail in Chicago. The two major drivers bring consumer challenges resulting in longer wait times and theft as Freddy mentioned. I personally prefer this option, especially when I am just picking up a few items but it can be frustrating to wait on someone insisting on using the self-checkout who has no idea how to use technology and continues to call on the support cashier… I’ll stop there! :/
    I had an experience similar to Freddy here in Chicago and it worked brilliantly. They recently opened an Amazon Bookstore near my home. In this bookstore, you can scan items as you shop using the Amazon App and make your entire purchase without ever approaching the register. Items are also slightly discounted through the app encouraging you to use this transaction method. I felt the whole experience was positive. The staff was able to mill about throughout the store assisting customers with needs at the point of sale and providing high-quality customer service, while the consumer was able to scan and quickly identify the price of a product without waiting in a line or having to ask for someone’s help.
    I also experienced something similar on a much larger scale a few weeks ago in Shanghai. The entire city (and most of the country) has adopted mobile payment capabilities, to the point it is rare to see anyone use cash or credit cards unless they are visiting. I understand that there is a communist component to government controlling how they operate but from an efficiency standpoint, it works very well. From bike rental, meal purchases, shopping, taxi and everything in between, the consumer simply swipes their phone and the transaction is complete. No waiting and no paper receipts. This doesn’t resolve the chit-chat situation but the transaction itself is quick and easy. They have also implemented a system where there is no need to wait for staff at the restaurant. There is a QR code on the table that you scan, the waitress has already linked your order to your table so you can scan and go as soon as you are ready. The apps are nicely integrated to allow you to share the expense with your dining companions as well.
    I will admit that I am a sucker for impulse purchases at the checkout so this type of distraction and marketing definitely works for a consumer like me and if I am totally honest, there are certain stores that I actually enjoy the checkout process for that very reason!

  5. Julia Eldridge says:

    I am glad that there was an article written about the wait time for 1 person with 100 items potentially being faster than 4 people with 20 items, as I have felt this affect a number of times. I often opt for the lines with fewer customers rather than fewer items, as I have noticed anecdotally that they seem to move faster. Once potential reason is in the set up time between customers. Often lines designated for fewer items have little space to place groceries, so the time for the transaction includes walking up to the counter, placing the items for purchase on at the register than the transaction itself. For normal lines, in the United States, there is typically a long conveyer belt to place items on. That means that as the person in front of you is wrapping up their transaction, you are able to ready all of your groceries so that they may be quickly scanned.

    When considering queueing patterns, I often think of Refael Hassin’s theory as described on the Freakonomics episode “What are you waiting for?” ( in which Hassin theorizes an optimal queueing pattern of having the newest customer go to the front of the line rather than the back. Though an interesting theory, there are many issues with the theory, primarily that it could not be used for goods that are needed such as groceries, as the person fourth in the line may never be served. While I do not believe this practice could work in the real world as it is today, I often find myself pondering its merits as I wait in lines and contemplate if it would be affective in the current situation.

  6. Michael Minor says:

    I enjoyed reading that article because I hate lines at the grocery store. I often use the self-checkout line for couple of reasons, one there is rarely a line and two I don’t have to wait for the person in front of me to finish writing a check. Yes, people in Indiana love to write checks at least when I’m in line. Customers perception of time is mainly based on their engagement. Self-checkout keeps the customer engaged throughout the process causing them to forget about time. You’re happy even if you spent four minutes trying to find the SKU for broccoli, just because you’ve avoided the other lines. In a conventional line, there is little to distract you other than some magazines you wouldn’t read or candy and chips selection you want to stay away from. I like Freddy’s idea of television; I suggest a small monitor that plays local news captions to keep people entertained.

    Costco is the only place that I can get behind a person with two carts and not blink an eye. They have a system where people are always moving and the customer engaged. There is a person taking your groceries out the cart at the same time the customer has there wallet out to show membership and getting to their method of payment ready, with another person bagging and carting. It’s a very smooth process that others could easily follow.

  7. Jordan McCroskey says:

    I’ve enjoyed the grocery store examples and the comments of the other class participants. I’m apparently in the minority as I loath self-checkout. Mainly because the software UI is bad and the scanning speed is slow. As this tech gets better I’ll be more willing to give it a chance.
    I am constantly amazed at the difference day to day when I go to Starbucks. Some days the line moves quickly and some much slower. I’m learning that the ability to preorder and have your drink ready and already paid for is key to a quick process. When I preorder I typically don’t wait – and my drink appears fresh and still hot. I think as more stores encourage a process that allows consumers to skip the line and prepay, the setup time will decrease (especially the time waiting for the person in front of me to pick all the options on their drink (it’s just coffee people and you’ve been standing in line – you should have your drink order ready to go by the time you get to the register).

  8. bairdjb says:

    Ok, I first have to say I had a great chuck at your terminology not that we all know you Sarah’s (i.e. “no need to tell it to have a good day, or to provide some sort of physical gesture to suggest warmth and appreciation” and “If we’re forced to accept a human”). Kim, I really enjoyed your venting at the beginning of your post.
    However, in all seriousness, I think that Kim and Sarah hit the proverbial nail on the head. I agree that in general a self-service line at the grocery store is perceived to be quicker when in fact it might not be the case. Although I see it as a competition/race and thus it is faster than checking out in a checkout line. Customers concept of time is skewed due to their high level of involvement and the reduced need for interaction outside of what is needed to complete the process. Conversely, I see self-service lines at McDonald’s and Panera drastically increasing the order placement times. This is do to the fact that unlike grocery stores the customer is required to search for the item to order in a process that is unfamiliar to the customer.
    Thinking specifically about retail stores. I think more stores need to adopt a process of identifying what a person is purchasing before they get to the checkout. There is no reason for the technology we have today that people need to load their carts, unload them again to be scanned and then placed back in the cart. This entire process needs to be streamlined. Which I guess honestly means we are coming to a point in time when there really is no need to go to the store. As the more efficient is simply ordering online either for home delivery or curbside pickup.

  9. Ruth Stone says:

    Admittedly, I am one of those people who tries to game the system to get through the checkout process as fast as possible. I view grocery shopping as a necessary evil. For that reason, I’d provide the following tips to service organizations as they design their check-out process to influence both the actual and perceived wait times:
    – Hire efficient, task oriented cashiers and baggers, measure their productivity and provide incentives for high performance (meaning the most people through per hour)
    – Provide training to their staff on how to be as efficient as possible in both of those roles
    – Ensure that cashiers have unobstructed views of the line for their lane
    – Consider using a serpentine line
    – Develop store values for customer service that guide staff on the priority of chatting with the customer versus moving them quickly through the process and out the door. My favorite checker at my local store greets me with a warm smile and about 10 words of chit-chat before moving me through the process with lightning speed. It’s hard to believe that anyone below the age of 65 goes to the grocery store to talk to the staff. If that were true, the call ahead orders would not be growing in popularity.

  10. Paul Aoun says:

    From research done in the Customer Experience field, specifically around perceived responsiveness of tools and User Interfaces, we know that change is key to make the users feel that time is shorter than what it actually is. For example, when the UI has an hourglass for few seconds and then switches to another UI, maybe with a “loading..” message, the perceived time is shorter than it actually is. So something similar in the queuing system will probably achieve the same result, maybe adding a counter for the remaining number of items to be scanned for the customer at the counter, or showing different messages on a big screen.
    As far as reducing the actual wait time, I can think of three ways to achieve that:
    1- Smart carts: add more “processing units” in the form of smart carts which can both scan the products as they are put in the queue, have a scale attached for measuring weight, and potentially a credit card scanner/Apple pay reader for payment. Given how affordable mobile devices are and ease of writing apps, this could be an economically viable approach to significantly reducing queueing time. If a fully-fledged smart carts are still too expensive and difficult to use, then at least basic services should be pushed out of the bottleneck to the carts.
    2- Look at redesigning the checkout, to separate the internal setup tasks and external ones:
    a. External: scan credit cards, and load purchased item on the belt (longer belts) before reaching the cashier
    b. Internal: greeting, bagging, and getting receipts
    3- Not a new idea but using single queues with some engaging activities while in the queue. There is a big electronics store here in the bay area using single queuing, and there is hardly anybody in the queue due to a fast flow rate.

  11. Peter Rigakos says:

    When looking down the line at cash registers it would be nice to see a large stack light indicator with the average check out time for each cash register. This would have to be done where it did not make the checkout person associated with being slow at their job, but simply an average. If the New York Times is correct in stating that we are saving a min because of the set up time associated with 5 people with 20 items vs 1 person and 100 items, then an indicator could show such an approximation to help with actual time vs perceived.
    Recently I read an article about Sam’s club implementing an app on your phone that allows the person to scan everything in their cart, check out over their phone, and walk out of the store. It did not mention anything about reviewing the items in case of theft, but I am sure they have thought of this. Such technologies will help even when entering a cash register/ check point where everything was scanned by the customer in advanced. At this point the check point would have all the info, and things could be prepare in advanced such as a bag person and additional help in reviewing the items list. Showing the customer things are prepared on their arrival the check point will help with customer service as well.

  12. Ken Janicke says:

    Perhaps adding an overhead clock at each checkout station that constantly updates as to the average customer checkout time would improve both the actual queue time, and the customer perceived queue time. It should be a simple matter to program such a clock display based on when the cashier begins with a new customer, and ends with the completed transaction.

    I believe this would facilitate customers ability to more quickly and accurately assess which line to enter based on the displayed average process time and the observed number of customers ahead in each line. This alone should more effectively distribute the customer checkout demand among the available processing stations, and reduce queue times.

    Customer perception would also likely be more aligned with reality, as they would observe actual rates and compare against the displayed average. Walking out to their car knowing they waited behind 2 customers in a line with an average 2 minute processing time, they can easily compare their observed experience and determine they waited only 4 minutes, plus or minus a minute, before being served themselves.

    Queue setup times can be reduced by layout designs that allow customers to pre-setup items to be processed while waiting in the queue. A simple example is the conveyor countertop, where customers pre-arrange their purchase items prior to reaching the checkout person. This allows the checker to continue the processing of item scans at a higher rate than if they were waiting for items to be handed or placed on the counter at the same time.

    With technology advancements, the next steps of queue setup time reductions will likely involve purchase item scanning and placement into tote containers prior to reaching the checkout location. Either by customer or some automated basket/cart method, this system results in simply remitting payment for the merchandise gathered, rather than re-handling, scanning, and sorting the items in front of a store employee.

    A possible marketing downside however, may be the alerting of customers as to the total value of goods selected prior to checkout. I’ve witnessed many people shocked at the final tally of their purchases, indicating that people will more easily overspend if they aren’t keeping track themselves as they shop. I’m not sure if this would have the effect of reducing the amount of impulse purchases to any measurable degree, or in reducing the processing time by those who are surprised and proceed to question the pricing or scanning procedure.

  13. Mike Carter says:

    I realize there are systematic approaches when it comes to designing flow systems for operational processes and personal wait time experiences, but there seems to be more of a psychological impact versus data driven fact. We have a newer grocery store called The Market District. The store using a single line design for checkout. There is a monitor that tells you what checkout line number to go to once you get to the front of the line. I don’t know that the line moves any quicker, but the perception is that no one can circumvent the system so you feel at ease. I do think this system allows the store to understand where the gaps are with the checkout employees because if Lane 1 is available more that Lane 3 over the same amount of time there could be issues that need resolved. As Peter stated, there is an app that can be used at Sam’s Club. We use this app every time. You scan the items as you grab them and have the exit door personnel scan the barcode on your phone when you leave. This is fast and easy to keep the flow moving and improve your shopping experience. If you have ever been to Disney World, you are well aware of the lengthy wait times. The “Fast Pass” option they created allows you to organize your day around key attractions that you want to see while ensuring that you will be able to see the attraction. The option alleviates any anxiety you may have about waiting in line and telling your family that you aren’t willing to wait in line. This system allows Disney the opportunity to review staffing needs, maintenance needs or potential capacity issues to address or possibly shut down attractions.

  14. Sara Moscato Howe says:

    I have to agree that I am one of those people who sizes up the line and will even line hop if I think my checker is moving slow. In recent months, I have forgone in person shopping for Amazon Pantry. You cant get perishable items through the pantry but you can easily get the other essentials, put them on auto renewal and they arrive at your door when you need them! I am also a huge fan of the Amazon Dash Button. I have several around my house so when I see something getting low, I just hit the button and it appears two days later! The more I can avoid the store, the better.

    Several stores in our area also offer grocery delivery. I haven’t tried it yet but I think I’m going to after reading this post! I also think this may be another reason delivery meals like Blue Apron and Hello Fresh have burst onto the scene… convenience!

    I do like the idea of virtual wait times with checkers, which may also appeal to those employees that have a competitive side, to speed up those wait times. It can also help a company set a standard and check it in real time.

    I also like the ‘scan as you go’ option, but do wonder about loss prevention in this model. The single line the moves people to an open teller is always a good fall back option. But truly, at the end of the day, I usually feel the problem is that the store has not matched supply with demand and more tellers are needed. That is very likely psychological on my part, but seems to be there is a delicate balance between matching employees to demand while keeping an eye on the bottom line of payroll costs. Think I’ll stick to Amazon and try that delivery service now! 🙂

  15. Rolando Saca says:

    It’s very interesting that Amazon is launching their “store of the future”, Amazon G, after four years of testing. Cameras are watching every customer so that there are no cashiers or registers anywhere. Shoppers leave the store through those same gate and Amazon account automatically gets charged for what they take out the door.

    We are so used to have everything so easy nowadays with on-demand content, same-day shipping and finding anything online. This test-run by Amazon shows brick and mortar is not dead yet. It’s just severely outdated. With technology such as RFID and others that have come a long way, I think it’s beneficial to brick and mortar retailers to put them to good use and eliminate queues altogether.

    I’m certain Amazon Go will spark much needed revolution in many brick and mortar companies in order to eliminate service times.

  16. Rolando Saca says:

    It’s very interesting that Amazon is launching their “store of the future”, Amazon Go, after four years of testing. Cameras are watching every customer so that there are no cashiers or registers anywhere. Shoppers leave the store through those same gate and Amazon account automatically gets charged for what they take out the door.

    We are so used to have everything so easy nowadays with on-demand content, same-day shipping and finding anything online. This test-run by Amazon shows brick and mortar is not dead yet. It’s just severely outdated. With technology such as RFID and others that have come a long way, I think it’s beneficial to brick and mortar retailers to put them to good use and eliminate queues altogether.

    I’m certain Amazon Go will spark much needed revolution in many brick and mortar companies in order to eliminate service times.

  17. srinivas tadepalli says:

    This is an interesting topic. Almost all of us have to deal with this if not daily, at least on a weekly basis. Folks here in this forum have talked about different methods from basic enhancements such as adding clocks above lines to sophisticated methods such as removing checkout lines altogether via the use of technology. Also, as pointed out, companies like Amazon and Krogers are testing new technologies where in they can remove the bottlenecks in the checkout process. I had the opportunity to visit the Amazon go store in seattle during Christmas 2017 and i must admit . though it looked spooky in the beginning, the overall experience was pretty smooth for a customer. A similar analogy i can think of is the ‘Circular runway” project in Netherlands (
    This idea cropped up as a result of bottlenecks in linear runway (similar to checkout problem in grocery stores). why cant we adopt a similar way in grocery stores. why should the checkout always be towards the end of the store. why cant a store have multiple entrances from multiple directions so that congestion can be avoided. ?

  18. D. Zekveld says:

    The future is here! “Amazon GO” eliminates the problem all together. Soon no cashiers, self or human.

  19. Camilo Rodriguez says:

    Definitely agree with Dave on this one. If the new amazon model proves to be successful, this will definitely be a worry of the past. People will just naturally get and recieve their products and leave. As this model proposes, the best alternative is to get rid of cashiers and lines all together!

  20. Anna Dietrich says:

    This article certainly made me pause and think about how much we wait in lines- most mornings to get coffee, in the office café for lunch, for a fitting room at local clothing store, at the stop light on the way home from work, for the restroom at the local bar, the list is endless. In a 2012 New York Time’s article, it estimated that American’s spent over 30 billion hours waiting in line that year. It’s hard to imagine what could be done in the time that’s wasted as we wait!
    Specific to this blog’s topic, I actually love to grocery shop, but loathe the anticipated line. As a grocery store customer I’m someone who organizes my items by “group” (fresh produce, heavy items, fragile items, household goods, etc.) so that like-items are bagged together and it’s easier to put away items back home- hence you can see I can appreciate some efficiency here!
    Similar to our EMBA 2019 SharePoint discussion on the Whole Foods and Amazon article, the way we shop is changing, therefore so is the way we wait. Now I have the option to have my groceries delivered, Target offers Restock for my everyday items, I can order ahead at Starbucks and Panera bread, and I can get ingredients/meal delivery right to my door.
    It wasn’t until I started this graduate program that I really realized the value of time, and grew increasingly impatient whenever it came to waiting or wasting time.
    As consumers have more shopping alternatives, brick and mortar stores are certainly going to be forced to rethink the in-store experience.

  21. Matt Slane says:

    Throughout the course I’ve become more aware of queue times. While at Disney we experienced the Fast Pass option where you get scheduled times to ride the high value rides instead of waiting in line. This was a great way to “jump” the line for 3 rides per day. However, it also drove expectations that this would be more flexible than it was. The most desired rides had an algorithm which limited the ability to select only one of these high value rides per 3 fast passes. Recently Disney has now announced that the visitors who stay at the premium Disney resorts have the ability to buy an additional 3 fast passes per person for each day.

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