Detention — What It Is, Types, and How It Works

Detention — What It Is, Types, and How It Works

Detention is a logistics term used to describe the time a carrier's equipment (truck, trailer, container, railcar) is kept waiting beyond an agreed free period while loading, unloading, or otherwise held by a shipper or consignee. It is both a practical performance metric (how long equipment is detained) and a commercial mechanism (charges applied for that extra time). Though often conflated with demurrage, detention has its own causes, rules, and impacts across road, rail, and ocean transport.

Why detention matters

Detention directly affects cost, capacity, and service reliability. When drivers or containers are held beyond free time, carriers lose productive hours and revenue; shippers face higher landed costs and strained carrier relationships; and supply chains suffer delays that can cascade into inventory shortfalls, missed delivery windows, or accelerated freight charges to recover schedule. In tight capacity markets, excessive detention can reduce effective truck turns per day and increase spot freight demand.

Common types of detention

• Truck detention — When a truck/trailer is delayed at a shipper or receiver beyond the agreed free time (often measured in hours). Carriers typically bill per hour after a grace period.

• Container detention — Applies to intermodal containers that have been pulled from a port or rail terminal and kept off-terminal beyond contracted free time. This is a common ocean carrier charge when importers hold containers for unpacking, inland movement, or customs processing.

• Railcar detention — When railcars are held at industrial sites beyond an agreed window, delaying the rail operator's ability to use the car elsewhere.

• Chassis or equipment detention — Specific to chassis used for container drayage; if a chassis is retained too long, detention fees can accrue.

Detention versus demurrage

These terms are related but distinct. Demurrage usually refers to charges for cargo or containers kept within a terminal or port beyond free time (the carrier or terminal charges for using terminal space). Detention applies when the container or equipment has left the terminal and is held externally. Practically: demurrage penalizes overstay at the terminal; detention penalizes prolonged use of a carrier's equipment outside the terminal.

How detention is calculated

Detention terms are governed by the service contract, bill of lading, tariff, or carrier agreement and commonly include:

• Free time — the allowed time without charge (e.g., 2 hours for truckloads, 24–72 hours for containers depending on region and contract).

• Grace period — a short additional window carriers sometimes allow before charging (e.g., 15–30 minutes for truck appointments).

• Rate structure — hourly or daily charges that escalate over time, often capped after a period or converted to a per-day flat fee.

• Billing increments — how detention is rounded (e.g., 15-minute increments or full hours).

Contractual and operational considerations

Clear definitions and measurement points matter. Agreements should define when detention begins and ends (e.g., arrival at dock vs. driver checked in at gate, when job is completed), who provides timestamps, and what constitutes proof. Many disputes arise from inconsistent start/stop points, lack of synchronized timekeeping, or poorly defined responsibilities for paperwork, customs clearance, or equipment return.

Example scenarios

Scenario 1: A truck arrives for unloading at 09:00 but waits two hours before a dock is available. If the contract allows 60 minutes free time, the shipper faces one hour of detention at the carrier's hourly rate.

Scenario 2: An importer picks up an ocean container from the terminal and keeps it on-site for five days to deconsolidate. If the free time is three days, detention charges apply for the extra two days of equipment use.

Technology and measurement

Modern logistics ecosystems use telematics, appointment systems, yard management, and electronic gate timestamps to capture objective arrival and departure times. EDI messages and TMS/WMS integrations can automate detention calculations and surface potential charges before they become disputes. Accurate data reduces argument friction and speeds up resolution.

Regulatory and trade nuances

Rules and typical free times vary by geography, carrier type, and trade lane. Port congestion, customs delays, and strikes can create systemic detention spikes. Some jurisdictions or trade contracts may place limits on maximum detention rates or require transparent tariffs.

Practical tips

To minimize the impact of detention: negotiate clear free time and measurement definitions, enforce appointment systems, ensure paperwork and customs are pre-cleared, and use data to identify chronic bottlenecks. For carriers, offer reasonable free time to stay competitive; for shippers, track detention spend as a supply chain cost and include it in carrier scorecards.

Bottom Line

Detention is a small term with big effects: it quantifies time lost and assigns cost to delays in moving goods. Understanding the type of detention, how it is measured, and where responsibility lies helps both carriers and shippers reduce friction, control costs, and improve throughput.