Dwell time is a facility-performance measure. It starts when the equipment arrives (or when the appointment window opens) and ends when loading or unloading begins, or when the equipment leaves. High dwell at a specific shipper or receiver is a predictable, repeatable cost.
It is related to but broader than detention. Detention is the billable portion of excessive dwell — the time past a free window that the carrier can invoice for. Dwell time includes that plus the "normal" wait that no one pays for.
Operations teams track dwell by facility so they can price it in. A lane into a receiver that averages four hours of dwell is not the same load as an identical lane into a receiver that turns trucks in 45 minutes, even at the same linehaul rate.
Example
A driver arrives at a grocery distribution center for a 0600 appointment, checks in, and is not called to a door until 0910. Unloading finishes at 1045. Dwell time is about 4 hours 45 minutes. If the facility allows 2 hours free, roughly 2 hours 45 minutes of that is detention the carrier can bill, subject to the rate confirmation terms.
Why it matters
Dwell time consumes the driver’s available hours of service. Two hours lost at a dock can be the difference between the driver legally reaching the next stop and having to shut down short of it.