Optimising Warehouse Workloads with Task Interleaving

Optimising Warehouse Workloads with Task Interleaving

Unlocking Warehouse Efficiency Through Task Interleaving

Many warehouse operations still rely on a traditional structure where teams are divided by function. One group handles goods-in, another manages stock movements, others focus solely on picking, packing, or dispatch. This model can seem sensible where each team owns a clear area of responsibility and managers benefit from simpler oversight. But beneath the surface, this siloed approach often leads to inefficiencies, especially when modern Warehouse Management Systems (WMS) are capable of orchestrating far more dynamic and productive workflows. At the heart of this capability is the concept of task interleaving.

In a conventional setup, workers and equipment are frequently used far below their productive capacity. Consider lift truck operators: they might move a pallet from the receiving bay to a storage location, only to travel all the way back empty to pick up their next assignment. Half of their journey contributes nothing to throughput. When these return legs accumulate across a full day, a significant amount of operational potential is lost.

Task interleaving tackles this head-on by transforming these empty journeys into productive ones. Instead of driving back with no load, the operator can be immediately assigned a task that begins nearer their current location, such as replenishing a pick face, relocating stock, or transporting goods from storage to dispatch. In a perfectly optimised environment, every movement becomes purposeful and continuous, creating a seamless chain of productive activity.

Of course, real warehouses rarely achieve perfection. Variability in order volumes, product mix, storage layouts, and equipment availability means that 100% utilisation isn’t realistic. Yet even a modest improvement, say a 25% uplift in efficiency, can deliver substantial financial value and justify investment in smarter systems and workflows.

Lift truck operators often run at around 50% efficiency simply because the return trip is spent travelling empty without completing any useful work.

Why a WMS Outperforms Manual Task Management

While warehouse teams can attempt to coordinate tasks manually, the complexity of modern operations quickly makes this unsustainable. Many warehouses already use a WMS to control basic task allocation, particularly in areas like picking or stock movements. These systems help reduce wasted travel, but as operational demands grow—multiple product sizes, varied order profiles, omnichannel workflows—the limitations of manual or partially automated management become clear.

This is where task interleaving demonstrates its real power. It blends resource management with task control to ensure that operators combine multiple complementary activities in a single trip. A picker might replenish inventory on the way back from a pick run. A forklift operator might handle internal stock transfers immediately after completing a putaway. By incorporating these micro-optimisations continuously, the warehouse reduces unnecessary travel and increases throughput.

Interestingly, this is a strategy we use unconsciously in daily life. We fill the car with fuel on the way home from the supermarket, or we drop off recycling while driving to pick up the kids. Combining tasks saves time and resources and task interleaving simply applies the same logic in a more structured way inside the warehouse.

What happens when the operational gains a business could unlock increases efficiency by even 25%?

Building a Warehouse Environment That Supports Task Interleaving

To make task interleaving work at scale, operations need to embrace a flexible, real-time approach to resource and task management. This requires moving away from siloed teams dedicated to specific areas of the warehouse and adopting a more integrated model where operatives can be assigned to any task they are qualified to perform.

Modern WMS platforms such as Principal Logistics Technologies’ ProWMS are designed to support this shift. They operate by establishing a clear set of parameters that define how tasks should be allocated, which resources are available, and where those resources can operate safely and effectively.

The configuration typically begins by defining all relevant resources: operatives, lift trucks, picking equipment, and any other assets involved in task execution. Attributes such as shifts, certifications, or downtime windows can also be assigned so that the WMS always has an accurate understanding of resource availability.

Next, warehouse zones are established. These could include distinct warehouse buildings, mezzanine levels, temperature-controlled areas, hazardous zones, or bonded storage. By linking resources to the zones they’re eligible to work in, the WMS ensures compliance and safety—for example, preventing untrained staff from entering hazchem areas.

Finally, each task type is associated with the resources capable of performing it. A worker without a forklift licence, for instance, would never be assigned a putaway task requiring lift truck use. This creates the foundation for a fluid and unrestricted task allocation system where operatives can be assigned in real time based on their location, skills, and proximity to the next suitable job.

Task interleaving is a resource-driven strategy that blends multiple tasks into one continuous workflow, reducing unnecessary movements across the facility.

Dynamic Task Allocation in Motion

Once these rules are in place, the WMS continuously monitors the position and status of each operative and asset. It then assigns tasks dynamically and in real time to ensure every movement contributes to productivity. The system acts as the decision-making engine, maintaining a steady flow of intelligently sequenced tasks that optimise labour, equipment, and storage infrastructure simultaneously.

This orchestration is what makes task interleaving such a powerful lever for operational improvement. By ensuring that workers and equipment are used effectively more of the time, warehouses benefit from smoother workflows, reduced travel, improved throughput, and enhanced service levels across both traditional and omnichannel fulfilment models.

The system automatically manages decisions and task allocation, ensuring a consistent workflow and maximising the utilisation of people and equipment.