Headhaul and Backhaul

Headhaul and backhaul are the two directions of a freight route. The headhaul is the direction with more cargo demand, where ships, trucks or aircraft travel full and freight rates are high. The backhaul is the return direction, where demand is weaker, space is plentiful and rates are low. On the main container route between Asia and North America, the eastbound leg to the United States is the headhaul and the westbound leg back to Asia is the backhaul.

The terms describe an imbalance between what two regions sell to each other, so they track trade flows rather than geography: a lane can switch direction if demand changes. In trucking, backhaul also means the load a driver picks up for the return trip, and a trip with no load at all is called deadheading. Both ideas connect closely to the cost of repositioning empty containers.

Imagine a taxi that takes a passenger from the city centre to the airport. Plenty of people want that ride on a Friday afternoon, so the fare is full. On the way back the taxi may find nobody to carry, and the driver will happily take a passenger at a discount rather than drive home empty. The trip out is the headhaul; the trip back is the backhaul.

Container shipping works the same way across oceans. One region sends far more boxes than it receives, so ships leave it full and return half-empty. Shipping lines charge what they can on the busy leg, because that leg has to pay for the whole round trip, and they cut prices on the quiet leg to fill some of the spare space. Exporters on the quiet side therefore enjoy cheaper freight.

Imbalances come from the shape of international trade. A region with a large manufacturing base and a trade surplus ships out more containers of finished goods than it receives, while a consumer economy running a trade deficit imports more boxes than it fills. The goods also differ: imports to North America and Europe from Asia are typically light, high-value consumer products packed in containers, while exports back are often bulky farm produce, scrap, waste paper and other commodities of lower value per box. Shifts in exchange rates, consumer demand and production locations can widen or narrow the gap over time, and these flows appear in the balance of payments.

A simple way to measure a lane's imbalance is the ratio of loaded volumes in each direction:

• $R$ is the imbalance ratio; a value of 1 means a balanced lane.
• $V_{h}$ is the loaded volume on the headhaul, in TEU.
• $V_{b}$ is the loaded volume on the backhaul, in TEU.

If a lane carries 1{,}000{,}000 TEU of loaded boxes eastbound and 400{,}000 TEU westbound, then:

Roughly 600,000 TEU of containers must go back empty, or be reloaded elsewhere, for the boxes to be in place for the next headhaul cycle. Because the round trip costs about the same either way, carriers recover most of it on the headhaul, so headhaul rates can be several times backhaul rates on strongly imbalanced lanes. Demand on the headhaul is also less sensitive to price than on the backhaul, a case of elastic demand on the return leg, where low-value exports only move if freight is cheap.

Moving empty containers costs carriers money for fuel, port handling and storage while earning no freight. Lines manage this by offering cheap backhaul rates, triangulating routes through third countries, using foldable or shared container pools and charging demurrage to get boxes returned quickly. In 2021 and 2022, during the pandemic surge in US imports, carriers often sent containers back to Asia empty rather than wait to load US exports, because the next headhaul paid far more. US farm exporters complained of lost sailings, and the Ocean Shipping Reform Act of 2022, signed on 16 June 2022, gave the Federal Maritime Commission power to act against carriers that unreasonably refuse export cargo.

For a business, which leg it ships on affects landed cost and margins. An importer on a headhaul lane faces higher and more volatile freight, which can feed into retail prices and inflation, while an exporter on the backhaul gains a cost advantage. The Incoterms in a contract decide which party bears that freight cost, and it is recorded in the shipping documents, such as the bill of lading, that banks review when paying under a letter of credit or financing a shipment through trade finance. Carriers on strongly imbalanced lanes can still gain from economies of scale by deploying very large ships on the headhaul.

• UNCTAD: Review of Maritime Transport
• Federal Maritime Commission