Trailer & Container Tracking

Trailer and container tracking is the function of a YMS that answers a deceptively simple question: where is this specific unit right now, and what is inside it? At facilities with dozens or hundreds of trailer slots, losing track of even a handful of units can quietly cost hours of labor every week and create serious detention exposure.

A tracking record typically follows a unit from the moment it enters the property to the moment it leaves. Beyond simple location, most systems capture load status (empty, loaded, partially loaded), seal integrity, damage notes, temperature (for reefer units), and the owning carrier or leasing company. For container operations at intermodal yards, tracking also includes chassis pairing — which chassis a given container is currently sitting on, since containers and chassis are often owned by different parties and billed separately.

• Current physical location (slot, dock door, or in-transit within the yard)
• Load status and seal number
• Owning carrier / leasing company and equipment type
• Time since arrival (feeds dwell time calculations)
• Chassis assignment for containerized freight

The technology used to keep this record accurate ranges widely by facility size and budget. Smaller yards often rely on a jockey scanning a barcode or entering a trailer number on a handheld device each time a move is completed — inexpensive and reliable as long as discipline is maintained. Larger yards increasingly use GPS trackers mounted on trailers, RFID tags read by gate and yard antennas, or computer-vision cameras that read license plates and trailer numbers automatically as units pass fixed checkpoints.

Even with automated hardware, tracking accuracy degrades without operational discipline. A jockey who moves a trailer without logging it, a driver who parks in an unassigned spot, or an RFID tag that falls off a trailer will all create a gap between the system's map and physical reality. Because of this, most well-run yards perform a periodic physical audit — commonly called a yard check or yard sweep — where staff physically walk or drive the lot to reconcile the system record against what is actually parked, correcting drift before it compounds.

Accurate location and dwell-time data is the foundation for detention and demurrage cost control — a trailer that has been sitting for six hours cannot be billed correctly, or acted upon urgently, if nobody knows it is there. The same data also drives yard planning: knowing exactly how many empty trailers, loaded inbound units, and outbound-ready trailers exist at any moment lets planners make faster decisions about when to request additional equipment or schedule extra dock labor.

Container yards, particularly those near ports or rail ramps, add complexity that trailer-only yards don't face: container size (20ft, 40ft, 45ft), stacking rules (containers can often be stacked, trailers cannot), and demurrage clocks that are governed by the shipping line or port authority rather than the yard operator. A YMS supporting container operations needs to track these attributes separately and often needs to interface with port community systems or terminal operating systems to stay synchronized on container status.