The Queuing Question

MICHAEL GARRY

One late Friday afternoon last month, the three-story Whole Foods Market at Union Square in New York City was, as usual, teeming with customers.

To accommodate what one shopper called the “insane” crush of Manhattanites toting their natural and organic groceries, Whole Foods designed a highly unorthodox checkout scenario. Its most distinguishing characteristic is a “single-queue system,” whereby one line of shoppers feeds a series of registers, with the customer at the head of the line taking the next available register.

At this Whole Foods store, there were actually two such queues, one for express shoppers (10 items or less) and one for shoppers with more than 10 items or those who wanted their purchases delivered (not unusual for Manhattan). The latter queue channeled customers to registers one through 16, which were configured side-by-side in three parallel rows perpendicular to the front of the store. The express queue served registers 17 through 34, which were side-by-side in two rows, similarly configured. (Whole Foods declined to comment for this article.)

The single-queue system has become a common sight at a broad array of consumer destinations, from airports and banks to post offices and book stores. Department stores like Kohl's and specialty retailers like TJ Maxx are also employing this checkout design.

Most supermarkets, however, remain tethered to the traditional mode of checking out shoppers — one line per cashier. Of course, there are good reasons for that preference. For one thing, supermarket shoppers often come with bulky shopping carts filled with merchandise, which take up considerable space in the checkout zone. Would a single line that stretched across the front-end area become an impassable barrier for other shoppers? In addition, grocers like to sell impulse items — candy, batteries and magazines — within each checkout lane. Would these sales be imperiled by a single-queue system?

Moreover, some supermarket chains, such as Publix Super Markets, prefer to offer the conventional checkout system because they believe some shoppers have favorite cashiers they like to use.

But a single-queue setup has its advantages. Perhaps its greatest plus is fairness: Each shopper is treated equally, first-come, first-served. They are not subject to the vagaries of individual lines, whereby one line with three shoppers can move more slowly than another line with six shoppers because the cashier in the former is still learning or one of the shoppers has dozens of coupons to redeem. And with a single queue, shoppers are spared the need to hunt for the best lines.

Single queues may also prevent shoppers frustrated with waiting from abandoning the line, said Bill Vetter, general manager and senior vice president of sales for queuing system provider Lawrence Metal. “With a single line, it's more of a commitment to stay in the line because walking off is more difficult to do.”

And single queues tend to thwart sweethearting — shoplifting in collusion with a cashier — since the cashier selection is random.

But the biggest question about single-queue systems — are they faster? — remains unresolved, at least in the supermarket environment. Some observers believe single-queue systems process more shoppers per hour than multi-line systems, but others contend there is no difference on average.

“One obtains the same [average] number of customers processed per hour” under either the single-queue or multi-line checkout system,” said Richard Larson, director of the Center for Engineering Systems Fundamentals at the Massachusetts Institute of Technology, Cambridge. “On the other hand, “the variance is higher in the multiple-line system,” meaning you can get stuck in a slow line.

Hannaford Tests

Whole Foods is not the only food retailer trying out the single-queue system. Trader Joe's has it in at least one store in Brooklyn, N.Y. Among conventional U.S. supermarket operators, Hannaford Bros., Scarborough, Maine, is testing the single-queue setup in at least seven stores, according to spokesman Michael Norton, who added that a decision on a wider rollout will be coming in the next few months. Two Hannaford Bros. stores known to be testing the single queue are in Milton, N.Y., and Dover, N.H.

But to go forward with a further rollout of a single-queue system, “we have to demonstrate that it's actually faster [than a conventional checkout], and customers need to believe that it's faster,” said Norton.

Lawrence Metal has started supplying what it calls “single-line queues” to drug chains such as Rite Aid and Duane Reade, newly acquired by Walgreens. The drug chains are not yet using LCD screens to direct shoppers, who instead are alerted by the cashier at the next available register.

Lawrence is also providing its system to a U.S. supermarket chain that did not wish to be named and is in discussions with at least two other major U.S. food retailers, said general manager Vetter, who added, “We're seeing the activity in drug stores cross over to the supermarket segment.” Supermarkets are also interested in applying the single-queue concept to self-checkout lanes, he said. Lawrence sells chains like Stop & Shop belts and posts for managing queues at the pharmacy and customer-service areas.

Single-queue systems are also being tested by U.K. food retailers. For example, Marks & Spencer is using electronic single queues from Q-Matic for the express lanes at 211 small-format food stores, said Terrence Green, board member of Q-Matic, Milton Keynes, U.K. Other U.K. food retailers employing single queues from Q-Matic for express lanes, he said, include Asda in about 15 stores and Waitrose in about 12 stores (both chains use them for self-checkouts as well). Q-Matic is supplying about 50 Wal-Mart stores in Canada and a similar number in the U.S. with single-queue systems for express lanes, said Green.

Self-checkout represents a good opportunity for single queues, said Green. “Customers will wait at the self-checkout, but they're not sure where. It's a bit of a mess.” Self-checkouts are also frequently held up by shoppers requesting help, he added.

Color-Coded Lines

The two single queues at Whole Foods' Union Square store don't actually look like the single queues at airports or banks that may curve around in serpentine fashion, guided by parallel retractable belts held up by short poles. In the express area at Whole Foods, the single queue is broken up into five parallel, color-coded lines. But the lines act as one because the first person at the head of each line is the next to be served, from left to right. (The bigger-basket queue is divided into four color-coded lines similarly configured.)

What all single-queue scenarios have in common is a leader — human or electronic — at the front who directs the next shopper to the next available cashier. At Whole Foods, an electronic screen above each queue area flashes the number of the next available register, and that number of announced at the same time, by a female voice in the express area and a male voice in the bigger-basket area. Each screen consists of parallel colored stripes corresponding to the color-coded lines; the register number for each line flashes within its corresponding stripe.

On the busy Friday afternoon last month, the four bigger-basket lines, separated by belts, held about six shoppers each. During one period, it took between three and 20 seconds for a new register to open up for the next shopper in line. In the express area, the five lines were each about 10 shoppers deep; it took between less than a second to 15 seconds for a register to become free there.

This reporter got into a bigger-basket lane (albeit with one item, a box of blueberries) and waited about six minutes before being served.

The single-queue system “works here,” said one shopper at the store. “It's better than the normal system.” Said another: “It's quicker than a regular supermarket. It works well.”

Hannaford Bros.' single-queue stores differ markedly from the Whole Foods store. For example, the Hannaford stores feature an undivided single queue at the front of the store. It serves all lanes with cashiers, regardless of basket size (there are no express lanes). A separate self-checkout area is operated conventionally with individual lines. According to spokesman Norton, at the Hannaford test stores, the single queue crosses the front of the store, sometimes turning once, sometimes not.

Hannaford Bros. employs a human line leader who directs the first shopper in the queue to the “best available lane,” said Norton. (No electronic screens are used). The best available lane presumably means the first open lane, though, according to an article last year in the Albany Times-Union, other factors may come into play, such as the experience of the cashier.

Hannaford alters the equation in favor of the single queue by adding a “queue buster” process. This involves an employee entering the queue with a handheld scanner and checking out a large order, which is wirelessly transmitted to a regular checkout for payment. In another queue-busting scenario, two shoppers (rather than one) are sent to the next available checkout, and the second shopper's order is scanned with the handheld.

Ruth Fantasia, a reporter for the Albany Times-Union, who wrote about the single-queue system at the Milton, N.Y., store last year, and has also shopped at that store, said she and her husband “generally like” the single queue. “It is much more efficient and faster than standing in line at whichever checkout lane you pick at a conventional store.”

At the Whole Foods store, the queuing areas afford little or no space for merchandising impulse items. By contrast, Hannaford sets up merchandise displays along the single queue in some test stores, though not in others, said Norton.

Lawrence's single-queue systems feature merchandise displays such as paneling, shelving and baskets within the line. Candy makers, magazine publishers and other brands are approaching Lawrence about exploring the single-queue merchandising opportunity at supermarkets, Vetter said. “It provides an opportunity to capture a shopper's impulse purchase earlier in the queue rather than when they are preoccupied with loading the belt.” All U.K. stores using Q-Matic's single queues have impulse merchandise set up along the line.

Some of the electronic screens deployed in the single queues at Marks & Spencer stores show video content in addition to numbers of the next available registers. “If you put brand information and entertainment in short hits on the checkout screens, you can get a message across with 10 times higher recall than other ambient screens around the store,” said Green.