Four-way shuttle automation on a mezzanine, above an existing carousel system
H&D Distributors, Inc. has delivered technical sealing solutions across diverse industries for over 40 years. Their Dallas facility needed to scale storage capacity without sacrificing the operational floor space already occupied by an existing carousel system. The constraint was clear: expand vertically, not horizontally.
Spacemaker designed and installed a QuadAxis Pro® four-way shuttle system on a structural steel mezzanine above the existing ground-floor automation. The result is over 500 pallet positions in previously inaccessible vertical space, with the carousel system below fully preserved and integrated into the same operational workflow.
The QuadAxis Pro® enables four-way pallet movement across the mezzanine — lane-to-lane flexibility in a compact footprint that a conventional racking solution could not serve. Shuttle operations and carousel operations coordinate through Spacemaker’s Traffic Control software and Warehouse Control System.
Vertical space recovered. Ground-floor operations untouched.
In a mid-sized facility where floor space is already committed to existing automation, the conventional response is to expand the building. The mezzanine approach eliminates that cost entirely — the QuadAxis Pro® system occupies cubic volume that was previously dead space above the carousel, delivering over 500 pallet positions without a single square foot of new construction.
The existing carousel system continues to operate exactly as it did before the shuttle installation. Both systems share the same facility but run on independent platforms, coordinated by Spacemaker’s control layer. The operation gains a full shuttle-automated storage tier without disrupting the workflows already in place below.
Project Photos
See It in Action
A facility at capacity on the ground. Unused volume overhead.
H&D Distributors’ Dallas warehouse had reached its horizontal storage limits. The ground floor was occupied by an existing carousel system that served the operation’s picking and fulfilment workflows — replacing it was not an option. But the building’s vertical envelope had capacity that no conventional racking approach could access.
The operation needed additional pallet storage that could be installed above the existing automation without structural compromise, without disrupting ground-floor operations during installation, and without requiring a separate control system to manage the new tier.
A shuttle system designed for a platform no one else would build on.
Spacemaker engineered the QuadAxis Pro® installation for a structural steel mezzanine purpose-built above the carousel footprint. The four-way shuttle capability is critical in this application — the mezzanine layout is compact, and the ability to move pallets both within lanes and between lanes means the system adapts to the available geometry rather than demanding it.
Spacemaker’s Traffic Control software and Warehouse Control System coordinate shuttle movements on the mezzanine with carousel operations below, giving H&D a single operational view across both tiers. The system supports lane sharing, zone redistribution, and real-time visibility across the full storage footprint.
System Specifications
Mezzanine warehouse automation and industrial distribution density
Can warehouse automation be installed on a mezzanine?
Yes. Pallet shuttle systems can be deployed on a structural steel mezzanine above ground-floor operations, recovering vertical cubic volume that conventional racking cannot reach. The mezzanine carries the racking structure, shuttle rails, and automated charging infrastructure as a self-contained tier.
Mezzanine installations suit facilities where the ground floor is already committed to existing automation or workflows. The H&D Distributors Dallas project is a four-way QuadAxis Pro® system installed on a steel mezzanine above an existing carousel system, designed to add 500+ pallet positions without disrupting ground-floor operations.
How do pallet shuttle systems integrate with existing warehouse automation?
Pallet shuttle systems can integrate with existing automation rather than replacing it, which matters for facilities where the existing infrastructure still performs well or where replacement costs would be prohibitive. The integration happens at the control-software layer.
At H&D Distributors, the QuadAxis Pro® shuttle system on the mezzanine coordinates with an existing carousel system on the ground floor through Spacemaker’s Traffic Control software. Both systems run on independent mechanical platforms but share a single operational view, with the Warehouse Control System managing task assignment and inventory state across both tiers.
What is warehouse density and how do you increase it in a constrained facility?
Warehouse density is the number of pallet positions a facility holds per square foot of building footprint. In constrained facilities — where the ground plan is fully committed and expansion is not an option — increasing density means recovering cubic volume that conventional racking cannot reach.
Pallet shuttle systems on a mezzanine address this directly by occupying vertical space above existing operations. The four-way capability of the QuadAxis Pro® matters in compact footprints because the system can navigate irregular geometry that two-way shuttles cannot.
How does automation reduce warehouse footprint in industrial distribution?
Industrial distribution operations often face the same constraint: an existing facility at capacity, no room to expand horizontally, and storage requirements that continue to grow. Automation reduces the apparent footprint of a warehouse by increasing what each square foot can hold.
Pallet shuttle systems eliminate the aisle space that conventional racking requires, deepening lanes and pushing more pallets into the same floor area. Mezzanine-mounted systems go further by recovering cubic volume above ground-floor operations entirely. The H&D Dallas installation does both — a four-way shuttle system on a mezzanine, recovering 500+ pallet positions in a footprint that already housed an existing carousel.
What is the ROI of mezzanine warehouse automation compared with facility expansion?
Mezzanine-mounted shuttle automation typically delivers faster payback than building expansion. There is no new construction, no permitting timeline, and no displacement of ground-floor operations during installation. Capital already deployed in existing automation continues to operate while the new tier handles incremental demand.
Specific ROI depends on facility geometry, throughput requirements, and the cost of the alternative — either renting additional space, expanding the building, or replacing existing infrastructure. Spacemaker scopes return-on-investment models per project during the design phase.
How do four-way pallet shuttles improve warehouse efficiency in compact spaces?
Four-way pallet shuttles travel on rails in all four directions, moving themselves across a storage grid without needing a forklift to reposition them between lanes. That capability matters most in compact and irregular footprints where deep-lane density is not viable.
Mezzanine installations are a clear example. The QuadAxis Pro® system at H&D Distributors operates inside a structural envelope that two-way shuttles could not serve, because the four-way travel adapts to the available geometry rather than demanding it.
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