Three clocks on one container

Free time starts when an import container is discharged. It can run out in two places: at the terminal, while the loaded box waits to be picked up, and on the street, while the container is out with you. Each place has its own clock and its own bill. A chassis under the box often adds a third.

Demurrage

Demurrage is a storage charge for a loaded container that is still at the terminal or rail ramp after its last free day (LFD). It is billed by the terminal operator or by the ocean carrier, depending on the port and the line. It keeps accruing each day until the container leaves the terminal.

Per diem, also called detention

Per diem is the ocean carrier's daily charge for keeping its container outside the terminal beyond the free days it allows. On an import, the clock starts when the container outgates and stops when the empty is accepted back at a return location the line has approved. On an export, it starts when you pull the empty and stops when the loaded container is ingated.

North American truckers usually call this per diem. Ocean carrier tariffs and US regulators usually call it detention. The word detention is also used for the time a truck waits at a customer's dock, which is a separate charge that you bill your customer. Keep the two apart in your rate cards and on your invoices.

Chassis per diem

If the chassis comes from a pool or a lessor, it carries its own daily usage charge from the time it leaves the pool until it is returned. If you own the chassis, the cost is still there, carried in your equipment budget instead of on an invoice.

Free days, rates and counting rules differ by line, port, terminal and contract. Some count calendar days and some count working days. Check the tariff or your agreement for each line you haul.

Who gets billed, and who causes it

The party that receives the invoice is often different from the party that caused the delay. Per diem is the clearest case. The motor carrier signs an equipment interchange agreement with the line (in the US, usually the UIIA), takes responsibility for the container while it is in its possession, and receives the per diem invoice. The days that ran up the bill were often spent at the customer's dock.

Several habits keep that cost with the trucker:

• Silent contracts. Customer rates mention the line haul and fuel and say nothing about per diem or free time at the dock.
• Late invoices. Per diem bills can arrive weeks after the move. By then the customer has paid, and nobody remembers why the box sat for four days.
• Missing evidence. Without gate times and delivery times, there is nothing to show the line or the customer.
• Small amounts. Each invoice looks too small to fight, so none are fought.

What usually runs up the days

• Late pickups. No appointment available, a customs or freight hold, or no driver or chassis on the day.
• Slow unloads. The customer keeps the box at the dock as extra storage.
• Missed return appointments. The empty is ready, but no return slot was booked in time.
• Terminals not accepting empties. The terminal stops taking that line's or that size's empties, and the driver comes back with the box.
• Weekends and holidays. Free days may keep counting while gates are closed or running reduced hours.

What it adds up to

Per diem is easy to underestimate because it arrives in small pieces. Here is an example for a mid-sized import operation. The numbers are illustrative; use your own.

Suppose that in this example, half of those days were spent at customer docks and your rates allow you to pass them through. Billing them back recovers 30 days × $125, or $3,750 a month. If five of the remaining containers became street turns that each avoided two days of waiting for a return slot, that is another 10 days × $125, or $1,250 a month.

Many lines step the daily rate up after the first few chargeable days, so long delays cost more per day than short ones.

Calculate your per diem exposure

The FMC billing rule in the US

The Ocean Shipping Reform Act of 2022 directed the Federal Maritime Commission to set rules for demurrage and detention invoices. The FMC's final rule took effect in 2024. It applies to invoices from ocean carriers and marine terminal operators for cargo moving through US ports. In brief:

• The right party. Charges may be billed only to the party that contracted with the billing party for the carriage or storage of the cargo, or to the consignee.
• Invoice timing. The invoice must be issued within 30 days of the date the charges last accrued. If it is not, the billed party is not required to pay it.
• Required details. The invoice must show identifying details such as the container number, bill of lading number and port, the free time allowed and when it started and ended, the dates and rates behind the charges, the total due, and who to contact to dispute it.
• Dispute window. The billed party has at least 30 days to request a fee mitigation, refund or waiver, and the billing party must resolve the request within 30 days of receiving it.

For truckers, the rule gives two practical tools: a reason to ask whether you are the right party for an invoice that reaches you, and a list of details to check before you pay. How it applies to per diem billed to motor carriers under equipment interchange agreements has been debated since it was published, so take advice on your own agreements before you rely on it.

The rule covers US ports only. At Canadian ports and rail ramps, these charges follow the line's tariff, the terminal's terms and your contracts.

Controls that keep the charges down

Track the free-time clock per container

Record the last free day, the line's free days outside the terminal, and the outgate date on every container. A list of LFDs in a spreadsheet tells you about demurrage; it says nothing about the empty that has been at a customer's dock for six days.

Alert before the clock runs out

An alert on the day after the last free day is too late. Dispatch needs to know a day or two before the LFD, and again before per diem starts on a container that is still out.

Pre-pull when the appointment falls after the LFD

When the customer's delivery appointment is after the last free day, pull the container to your yard first and deliver from there. Yard storage and the extra chassis days are real costs, so price them in your rate card and bill them.

Street-turn the empty

An import empty that can carry an export booking with the same line skips the return trip and the wait for a return slot. Our street turns guide covers when that is allowed.

Keep gate timestamps as evidence

Disputes are won with times: when the box left the terminal, when the truck arrived and was released at the dock, when a return was refused, and when the empty was ingated. Keep the interchange receipts that show them.

Bill per diem back to the responsible customer

Put dock free time, per diem and chassis days in your customer rates, with how each is charged. Then bill it on the same invoice as the move, with the days and dates that support it, so the customer can see why the charge is there.

Per diem is rarely one large mistake. It is many small delays that nobody saw in time and nobody billed. Each control above makes the delay visible sooner or puts the cost with the party that caused it. If you would like to see them on your own containers, request a demo.

What a street turn is

Without a street turn, an import and an export with the same line are two separate jobs. The import is pulled from the terminal, delivered, unloaded, and the empty goes back to the terminal. For the export, a driver pulls a different empty from the terminal, takes it to the shipper to load, and brings it back full.

With a street turn, the import empty goes straight from the consignee, or from your yard, to the exporter. The empty return and the empty pickup both disappear.

When it's allowed

The container belongs to the ocean carrier, so the line decides. The conditions below are common; the details vary by line, port and agreement.

• Same ocean carrier. The export booking must be with the line that owns the container, or with a line that has agreed to use that equipment.
• Matching size and type. A 40-foot high cube fills a 40-foot high cube booking. Substituting a different type needs the line's agreement.
• Carrier approval. Most lines want the turn approved before it happens, through their own portal or a street-turn platform, linking the import container number to the export booking. Some charge a fee.
• Interchange. In the US, the move usually runs under the UIIA, and you stay responsible for the container until it is ingated. If a different trucker will haul the export, the handover is a street interchange that both carriers and the line must agree to. Outside the UIIA, the line's own interchange terms apply.
• Container condition. The empty must be clean, dry, undamaged and suitable for the export cargo. Food-grade loads need a food-grade box. Inspect it and photograph it before it goes to the shipper.
• Timing. The empty has to be ready when the export needs it, and the export has to load and return between its earliest return date and cut-off.

If the container will cross the Canada–US border on its next move, check the customs rules for international equipment before you plan the turn.

What a street turn saves

• Two terminal visits. No empty return and no empty pickup, so no gate queues and no appointment slots for either one.
• Miles. The trip from the consignee to the terminal and from the terminal to the shipper becomes one trip from the consignee to the shipper.
• Per diem days. An empty that would sit in your yard waiting for a return slot, or because the terminal is not taking that line's empties, goes straight back to work.
• Congestion. Fewer empties at the terminal and fewer truck moves at the gate.

How free time is counted across a street turn depends on the line. The container often stays on one per diem clock from the import outgate until the loaded export is ingated. A turn that waits too long for its export can cost more than it saves, so plan the two moves close together.

Here is an example. The numbers are illustrative; use your own.

Calculate your per diem exposure

Why carriers miss them

Most carriers who haul both imports and exports for the same lines have street turns available every week. They go unused for ordinary reasons.

• No shared view. Imports and exports are planned by different people, or on different sheets. Nobody sees the empty and the booking on the same screen on the same day.
• Short windows. A match often exists for a day or two. By the time someone notices, the empty has been returned.
• Approval friction. Requesting approval takes a login, a form and a wait. On a busy morning it is quicker to send the empty back.
• Scattered details. Line, size, type and condition live in different emails, so checking a match takes longer than the match is worth.

How Drayvia finds street turns

Drayvia compares import empties with open export bookings by line, size and type, and location, and checks them against the export's ERD and cut-off. Candidates appear on the dispatch board, and Watch lists each one as a street turn available, next to the other loads that need a person.

A dispatcher reviews the candidate, requests approval from the line as usual, and accepts the turn. Drayvia then plans both moves together: the import delivery, the move to the exporter, and the loaded return. The driver gets the legs in the app, and the per diem days on the container stay visible on the load until it is ingated.

Where to start

• List the lines you haul both imports and exports for. Those are where street turns are possible.
• Read each line's street-turn terms: approval method, fees and any limits on area or equipment.
• Ask drivers to photograph every empty at the consignee before it leaves.
• Check for matches every morning before empties are sent back.

For the wider picture on free time, read our guide to per diem, demurrage and detention. To see matches on your own loads, request a demo.