Queuing is the process of moving customers from a central location to a specific place or service.
Waiting in lines is something everyone does. Lines are encountered everywhere, ie. at the airport; checking into hotels, etc, etc. Customers can be left confused as to what line to stand in, what counter to go to when called and distracted by noisy and crowded environments.
SPF - Shortest Processed First
The restaurant model is often used to describe SPF – a group of 8 may have to wait longer to be seated than a group of two if there are more tables for two than for eight. SPF more accurately describes a model where transactions of short expected length are dealt with sooner – as in a 10-items-only queue in a supermarket.
SPF can work well but is problematic if consumers do not perceive the right degree of fairness from the system. It is necessary to explain why customers are being served in an order other than simple First In First Out and ensure that consumers understand and see the logic of this alternative approach.
In service models where different standards of service are expected at different levels of cost, SPF is widely accepted, as in airport check-in desks where Business Class passengers are checked in more speedily. This is acceptable for other passengers generally because they understand that the extra service has to be paid for. Where no such class or cost distinction exists, SPF is potentially divisive.
First In First Out (FIFO)This is the model of service provision which is most visibly fair, where each customer is served in the order in which they registered for service. In service models where all customers think of themselves as equal, this model is important.
Single Queue (SQ)
This is the familiar snake or corral queue format. Each person waiting is served in turn and the format of the queue discourages pushing in. It also provides visible reassurance to customers that they will be served fairly and that the queue is progressing.
SQ is ideal where deviation of service times is moderate and where individual transaction times are not long – say under 7 minutes. The queue forms a buffer of customers ready to be served and is hence efficient in server utilisation terms.
The single queue works well when the direction and structure of the queue is defined by physical features – like queue barriers.
Multiple Queues
This is the format seen at supermarkets – a number of individual queues with no filtering of customers. Although this makes good use of floor space, customers feel obliged to hunt for the shortest queue.
Where the service model involves a wide range of potential service times, customers can find themselves waiting for much more than the statistical average service time and this frequently breeds resentment or anxiety.
Whilst the overall arithmetic mean service time across the entire store may be perfectly acceptable, the variation in the individual consumer’s experience (manifested as the standard deviation of waiting time population) is huge.
Multiple queue is most appropriate for low-value transaction models where a low level of service is accepted by customers.
Diffuse Queue
Take-a-ticket queue models are examples of diffuse queue. There is no formal queue line but customers register their place in the process with a ticket.
Diffuse Queue allows customers to browse if they want to while in the ‘notional’ queue. Diffuse queue is often thought of by consumers as primitive as they have no means of estimating when they will be served and feel obliged to continually monitor the ticket number being served.
More sophisticated versions provide zoned service or expected time for service information to be displayed. These systems are more successful in encouraging customers to browse, or at least move away from the ticket dispenser, making its location easier for other customers to see.
Diffuse queue is the most flexible model when a large standard deviation in transaction length is likely.
Head of Queue
This is the place where the next person to be served waits in a single queue environment. It’s vital that they can see along the line of service positions to avoid significant gaps in service provision. With more than 5 checkouts, this factor becomes increasingly significant.
Line of sight from the head of queue is an important consideration for layout designers. Service point 1 should be closest to the head of queue, and the till numbers should increase from left to right.
Queues must be fair
The most common queue model is also the model that is most visibly fair – in that it serves people in the order in which they arrive.
There are other models but the First-In-First-out model embodies the fairness that we’ve come to expect.
When a queue forms it is critical that people feel they’ve been treated fairly. A queue system that discourages ‘pushing in’ eliminates many of the psychological issues that contribute to stress in the queue.
Queues must be managed systematically and not allowed to descend into a free-for-all
Clear evidence that the queue is being managed by the service provider is important. If a system is not in place, those waiting will not be confident that the service provider values their time appropriately.
A managed process is a clear signal to the consumer that they will be served in time and their patience is rewarded.
The process must include positive feedback of progress
Clues that allow a consumer to estimate their own likely waiting time, or at least understand that the queue is progressing, provide reassurance that the wait is not an uncertain one. This is especially the case when a call-forward system is in use. The visual and audible signals provide evidence that those in the queue are being served in sequence.
The process must be clearly identified; start & end points must be visible
Consumers must be able to see clearly where they go to join the queue. This is part of ensuring those about to wait understand that they can register their having joined the queue for service.
The direction of the queue and the end point must also be visible, so that those in the queue know they are travelling in the right direction and can find their way out after service.
Where more than one queue is in operation, perhaps for different types of service or goods, it must be clear to consumers what the purpose of each queue is. Clear signs that are easily understood and difficult to misinterpret are essential for this.
Perception of waiting time should be managed
The time a person spends in a queue is often different to the time they feel they have spent, or anticipate they will spend.
Consumers frequently over-estimate the length of time they will spend in a queue when they can’t see evidence of a system or of progress within that system. Providing feedback reduces this likelihood.
If some form of relevant distraction can be provided this can be used to reduce the perception of time spent in the queue. However, this distraction must be either relevant to the transaction or to the person waiting, or ideally both to some extent. If neither of these cases applies then the distraction is most likely to be seen as an irritant. Even where a specific form of relevant distraction isn’t provided, consumers who get clues to the progress of the queue will be distracted, in a positive way.
When a queue layout is created, an access route is effectively created. With the increasing expectation that all members of society are served equally, it's vital that a queue layout doesn't make using the service unreasonably difficult for disabled people.
What must also be considered is most places in the UK that are open to the public are now required to comply with the Disability Discrimination Act (DDA) 1995. It states that service providers now have a duty to:
Compliance of the DDA can be easy if service providers plan ahead. When it comes to most crowd management products, there are 2 simple steps: start with compliant products and install them with the appropriate amount of spacing.
If an alternative pathway for people in wheelchairs is available that provides equal or superior access, it is acceptable for the queue to have a narrower pathway than is normally required. Note, however, that providing an alternative pathway does not relieve a facility of complying with regulation regarding “protruding objects” in other words, it is still important to use compliant posts, even if there is on offer an alternative pathway to people in wheelchairs.
The Disability Rights Commission has published a practical guide on making access to goods and services easier for disabled customers. One section, Getting to goods and services, covers the area of Queuing systems:
Queuing systems, waiting areas and seating
If customers have to wait to receive a service, or to walk considerable distances within the premises, circulation space should be considered and whether it is possible to provide suitably designed seats for people with mobility impairments to sit and rest. In very small premises where there is not enough space to provide seating adjacent to queuing areas, it is important to make alternative provision for customers who cannot stand and wait. Any such arrangements should be made publicly known to avoid customers getting upset if they think other customers are queue jumping.
Once the customer has reached the front of the queue, they approach the counter, service desk or checkout:
Counters, service desks and checkouts
Thought should be given to how disabled customers get to and use counters, service desks and checkouts. Consideration could be given to fitting an induction loop system at counters with glazed screens or where there is background noise to help people with hearing aids.
Consideration also given to the queuing area in respect of:
The above information was collected from the following sources:
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Last updated: 02.10.2008 © Copyright reserved