For decades, the standard metric for warehouse inefficiency has been “travel time”—the hours operators spend walking up and down aisles pushing carts to locate inventory. In facilities with high Stock Keeping Unit (SKU) counts, walking can consume more than 50% of a picker’s shift.
When warehouse managers are struggling with labor shortages, high turnover, and slow order cycle times, they typically look to two distinct architectural solutions to optimize the picking process: traditional Engineered Pick Modules and fully automated Goods-to-Person (G2P) Automation.
At Precision Warehouse Design, our engineering teams evaluate your throughput volume, order profiles, and facility footprint to recommend the ideal fulfillment engine. Because we are vendor-neutral integrators, we look strictly at the data to determine which system will generate the fastest ROI.
Here is an objective comparison of traditional Pick Modules versus G2P automation.
Engineered Pick Modules: Rack-Based, Flow-Driven Manual Picking
A pick module is a high-density, multi-level storage structure engineered to consolidate fast-moving inventory into a space-efficient footprint. It is important to note that pick modules are a traditional Person-to-Goods methodology and are significantly less automated than G2P solutions.
Typically, these systems are rack-based, utilizing carton-flow or pallet-flow racks that feed directly into a central conveyor system. A worker physically walks the aisle, manually picks the item from the flow rack, and places it onto the takeaway conveyor to route the order to the next zone or packing station.
PWD System Capabilities & Partners
We design custom pick modules utilizing robust structural components and advanced picking technologies to optimize this manual process:
- Structural Support & Mezzanines: Steel King, Interlake Mecalux, Cogan, and Wildeck.
- Gravity & Flow Systems: Mallard and Unex carton/pallet flow lanes for continuous replenishment.
- Integrated Conveyors: Hytrol and MHS systems for rapid order routing between zones.
- Picking Technology: Integration with Lightning Pick (pick-to-light) or Zebra (RF scanning/voice picking) to drastically increase speed and accuracy over paper-based picking.
Operational Profile & Strengths
- High-Volume Velocity: Extremely cost-effective for highly predictable, fast-moving SKUs.
- Continuous Flow: Excellent for high-volume case or piece picking where orders flow smoothly from zone to zone via conveyor.
- Capital Efficiency: Generally represents a lower initial capital expenditure (CapEx) compared to full robotics, while still delivering a massive leap over static shelving.
The Trade-offs
- Labor Dependency: Workers still must walk the module and manually pick items (person-to-goods).
- Replenishment Congestion: If not engineered correctly, manual replenishment can disrupt active picking in high-velocity zones.
Goods-to-Person (G2P) Automation: Robotic Delivery & Zero Travel Time
Goods-to-Person automation flips the traditional fulfillment model entirely. Instead of workers walking aisles or navigating pick modules to find inventory, intelligent robotics and automated storage systems retrieve the exact item and deliver it directly to an operator stationed at an ergonomic workstation.
G2P entirely eliminates search and travel time, radically boosting pick rates and addressing severe labor bottlenecks head-on. This category focuses heavily on robotics and includes automated pick systems, Vertical Lift Modules (VLMs), cube-based AS/RS, and automated put walls.
PWD System Capabilities & Partners
G2P is not a single technology, but a category encompassing several advanced automated solutions. We partner with top-tier brands to configure the right engine:
- Cubic-Based AS/RS: Systems like Kardex AutoStore utilize a dense 3D grid with robots operating on top to retrieve bins, serving as the ultimate high-density storage.
- Vertical Lift Modules (VLMs): Kardex Shuttle VLMs deliver trays to operators at ergonomic heights, maximizing vertical warehouse space.
- Autonomous Mobile Robots (AMRs): Fleets from Caja Robotics and Mushiny dynamically transport inventory racks directly to pickers, offering unparalleled layout flexibility.
- High-Speed Sorting & Fulfillment: Systems like OPEX Perfect Pick for automated inventory routing and OPEX SureSort for order consolidation and automated put walls.
Operational Profile & Strengths
- Eliminates Walking: Operators remain at fixed stations, frequently doubling or tripling pick rates compared to manual picking.
- Maximum Footprint Utilization: Systems like AutoStore or VLMs capture wasted vertical space, often preventing the need for costly facility expansions.
- High Security & Accuracy: Inventory is securely enclosed and managed by software, virtually eliminating shrinkage and picking errors.
The Trade-offs
- Higher Initial CapEx: Requires a larger upfront investment in robotics and control software compared to rack-and-conveyor systems.
- Rigid Item Profiles: Bins and totes have strict size and weight limits, meaning highly irregular or oversized items may still require secondary picking methods.
System Comparison
| Engineering Criteria | Pick Module Systems (Manual Person-to-Goods) | Goods-to-Person (G2P) Automation |
| Primary Labor Impact | Organizes and shortens the walk; worker manually picks to a conveyor. | Eliminates the walk entirely; robots deliver goods to the worker. |
| Ideal SKU Profile | Predictable, high-velocity fast-movers (the 80/20 rule). | Massive SKU proliferation; medium-to-slow movers. |
| Footprint Efficiency | Good (Utilizes mezzanines for vertical space). | Excellent (Ultra-dense cubic or vertical storage). |
| Capital Investment | Low to Moderate. | Moderate to High. |
| Scalability | Requires physical structural additions. | Add robots to a grid/fleet, or add VLM units. |
The PWD Verdict: Which System Should You Choose?
Choose a Pick Module System If:
You have a highly predictable order profile with a concentrated group of fast-moving SKUs. If your primary goal is to organize your fast-movers using carton flow and conveyors for high-speed picking without the CapEx of full robotics, a module integrated with pick-to-light technology is incredibly cost-effective.
Choose Goods-to-Person (G2P) Automation If:
You are struggling with severe labor shortages and have a massive, diverse SKU count where workers spend the majority of their day just walking to find items. G2P automation is the optimal choice for eCommerce, 3PLs, and micro-fulfillment centers that need to maximize vertical space, ensure 99.9% pick accuracy, and decouple throughput from headcount.
Ready to Solve Your Picking Bottlenecks?
Whether you are replacing static shelving with a multi-tier Pick Module or leaping into a fully automated AutoStore grid, PWD manages every step of the process. Contact our team today to get started.
