Case study

The problem with warehouse congestion

May 26, 2023 | Pallet Racking

A successful warehouse is energised by the strategic and uninterrupted movement of goods, people and equipment. Everything that needs to move does move in a streamlined and timely fashion. This creates a smooth functioning operation with high levels of efficiency; however the build up of warehouse congestion could soon put a stop to this.

There’s much expected from the modernistic warehouse. Working to meet heightened demands whilst operating at a much faster pace in order to stay ahead of the game, with magnified stock levels and an ever-expanding workforce, the task of keeping warehouse congestion at bay becomes much more challenging, particularly once the warehouse reaches 85% occupancy.

So, is warehouse congestion holding you back from taking an industry leading position?

What is Warehouse Congestion infographic

What is warehouse congestion?

The term ‘warehouse congestion’ is used to describe the abnormal standstill of natural warehouse movement. Areas of the facility become motionless and over-crowded as travelling units enter a bottleneck situation which initially forces a significant slowdown followed by a complete halt in movement. This results in the accumulation of stationary units, unable to move freely and it’s a situation that can drag on for quite some time. The task of easing congestion begins at its originated area, so it could be quite some time before the backed-up units are able to move forward.

The consequences of warehouse congestion

The effects of warehouse congestion are overspreading to the point where the scope of the impact goes far beyond the physical four walls of the facility. This is because congestion causes the deceleration of activities within the supply chain which will ultimately result in customer expectations not being met. When performance is hindered, so is profitability and if that’s not enough, it triggers the opening of new opportunity to the industry competition, making the consequences of warehouse congestion quite severe.

Tell-tale signs of congestion in your warehouse

If your operation is suffering from warehouse congestion, there will be a number of warning signs including:

Specific areas becoming over-run by too much activity – Where there’s congestion, there’s often too much heightened activity all within a limited area. The picking and replenishment of stock at the same time is a good example of this. Hi volume picking and loading in the same space can delay the individual processes significantly. There’s a lot of stopping and starting and much waiting around as each process try to work around the other within a confined area.

Frequent traffic jams –You’re likely to notice frequent queues as multiple vehicles and people often travel towards the same location at the same time. Frequent high traffic volume is often the result of congestion elsewhere in the warehouse and this forms part of the ripple effect.

A drop in customer satisfactory levels – When it comes to order fulfilment, congestion will cause delays and confusion, so if you’re seeing a rise in returns, a reduction in orders or an increase in negative feedback, congestion could be at the very heart of the problem.

Rising labour costs with lower productivity – Is your operation utilising extra, temporary labour yet productivity remains low? This may be because the issue is lack of movement rather than heightened workloads. Whilst it may seem a logical thing to do, adding more workers to the crowd who are all trying to achieve the same thing and at the same time, will only add to the congestion.

Tell-tale signs of congestion in your warehouse

How congestion affects specific warehouse areas

Wherever congestion originates in the warehouse, it doesn’t take long for other areas to become effected. Congestion will spread rapidly throughout the facility impacting five crucial areas of the operation:

Goods received – Being the starting point of the inventory journey, if the goods received area becomes congested; the effects will ripple across the rest of the operation. It’s here where inventory documentation, counts and inspections are at risk of inaccurate recordings and lost sales are the ultimate price. The inability to record accurate inventory information can lead to misinformed customers who are likely to look elsewhere, cancel or return orders.

Storage – The home for inventory during the interval between entering and leaving the facility is the storage area. Whilst it’s the largest section of the facility, the area can become congested if increased inventory volumes mean capacity has been reached. You’ll find that newer stock has nowhere to go and trying to find an appropriate storage space will become labour exhaustive and time consuming creating a busy, unorganised and slow moving area.

Picking – The picking process is an integral part of the order fulfilment process, therefore congestion in this area of the warehouse can be truly damaging. Whilst the pickers struggle to get to the required items, the order process is being delayed at the cost of customer dissatisfaction.

Packing – An overcrowded and chaotic order packing environment can be full of distractions and feel uncomfortable to work in. Congestion here is the response to unnecessary delays earlier in the process which causes the late and mass arrival of picked inventory, rather than it arriving in a steady stream. This can lead to mistakes when packing a specific order for a customer who could end up receiving incorrect or missing items. The packing process requires adequate space and time to complete the task in hand, something which a congested environment cannot provide.

Shipping –This is the final stage of the operational process, however the continuation of delays throughout the operational process can result in an overwhelmed shipping area. The area may go from clear, quiet and calm to crammed, busy and chaotic in a matter of hours as the aftermath of the congestion in the rest of the warehouse piles into the shipping area. The space can be filled quite quickly leaving inventory disorganised as it waits to leave the building which makes the shipping process more complex and time consuming.

The best remedies for warehouse congestion

Improve inventory control – From the point of goods received to shipping, inventory must be documented and tracked appropriately. This prevents unnecessary stock accumulation which drives congestion, whilst improving availability which contributes to meeting customer expectations.

Incorporate stock rotation assistance – Stock rotation is an absolute must for many operations, particularly those managing perishable consumable goods; however the task of checking dates manually can delay the picking process and congest the area. There are a variety of storage systems available that operate on the First-in First-out (FIFO) method which means inventory is stored and picked in date order without the need to manually find the closest shelf-life products. When using these systems, the picking and replenishment activities take place on opposing sides of the structure which eliminates the risk of congestion if both activities were to be carried out at the same time.  Without the need to hang around to check dates whilst loading and picking stock, occupancy of the area is fairly quick when completing these tasks and this helps to prevent a build up of activity. Systems that work on the FIFO method include pallet live racking, the shuttle racking system, the drive through racking system and the carton live shelving system. All systems implement a simple loading and picking process and an overall streamlined operation.

Carton Live shelving

Maximise space utilisation – By using the space you have wisely you can eliminate the biggest contributor to warehouse congestion. Limited space can be the biggest hindrance when faced with growing inventory volumes, business activity and workforce. Every inch of your space from floor to ceiling, wall to wall can bring value to your operation if used optimally. Even if it seems that there is no opportunity to accommodate continual growth, try looking up! When you do are you staring at fresh air and the long distant ceiling of your building? If you are then you could actually be staring at a perfectly functional space, you just need to know how to use it! Did you know that however tall the ceiling, storage systems can go just as high! Take the VNA racking system for example. The structure consists of racks as tall as the ceiling whilst standing much closer together when compared to a standard wide aisle racking configuration. With a combination of narrower aisles and taller racks, storage capacity is instantly increased, and by a significant amount too! Another way to transform overhead fresh air into a useful, productive area could be a warehouse mezzanine floor installation which creates a floor level above the ground floor. This new space can be used to accommodate additional storage or production spaces or even an office area to support your growing office team.

Multi tier storage mezzanine

What if height space is not quite so giving? Well, you could consider a more compact storage configuration with the incorporation of deep lanes rather than an aisle between each row of racks. There are a number of pallet racking types that offer this solution with some operating on the FIFO method as mentioned previously and others on the First-in First-out (FILO) method. Because there is no need for separate loading and picking faces, the system which operate on the FILO method tend to be a little more dense. These include the push back racking system or the drive-in racking system.

Ensure the display of appropriate signage –These can be used to prevent items and people from occupying the wrong areas and take up room unnecessarily. Instead they are directed to their own dedicated zones with the use clear and easy to read signage, and this will help to prevent goods, people and departments from becoming muddled up and overcrowded.

With more inventory than your structures are designed for, it could be easy to try squeezing as much as possible into the storage structures; however something to be cautious of here is the danger of pallet racking overload. Operators must be aware of the structures maximum weight load at all times and an effective way of communicating this would be to display weight load notices.

weight load notice

Optimise your layout – Effective directional flow is a real technique designed to prevent congestion and is motivated by a purposeful warehouse layout design. From the point of goods entering the facility to leaving it, the route followed should be singular, otherwise the back-and-forth motion of goods, people and vehicles is likely to become a regular occurrence and this will encourage congestion. Depending on the location of the entry and exit points, the most optimal route my be L, I or U shaped. Consider the various activities and departments in your facility including their location and how much space each is currently occupying. Some may have too little space in which to operate whilst others have more than they need, therefore a little reconfiguration work could be all that’s needed to alleviate congested areas. In addition, assess the position of each individual department to distinguish whether their location is facilitating unnecessary travel which can congest routes.

Diagrams illustrating the L I and U shaped flow layout

Consider a reshuffle of working hours – If your operation is growing, that will likely result in a larger workforce working to meet heightened demand. For many warehouse operations, this amount of activity being carried out within a limited time frame can become a squeeze and congestion sets in. Introducing shift patterns, despite the additional costs can be very effective and ultimately improve overall throughput performance and profitability, making it a worthy investment. With less bodies moving around the facility at once, operators can carry out their duties in a much calmer environment with minimal frustration and without being held up by congestion.

Staying ahead of future congestion

Warehouse congestion is clearly problematic, however early detection and effective actions can improve speed and reduce costs. If a rising number of SKUs, a larger workforce, in-effective space usage or low productivity is giving you cause for concern and your looking for advice on cost-effective solutions, speak to a WSL expert today! Call us on 0113 2045350 or email

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