Measurement, Impact, and Management of Port Congestion: An Analysis of Bottlenecks in the Global Container Supply Chain

Introduction

Port congestion has evolved from a cyclical disruption into one of the most persistent operational challenges in the global ocean shipping supply chain. The definition given in Kpler's "Port Congestion: A Guide to Measurement, Impact, and Management," published on November 25, 2025, is: congestion occurs when the volume of vessels seeking to call at a port exceeds the terminal's ability to efficiently handle those vessels. Its consequences propagate through the supply chain level by level, affecting schedule reliability, inventory positioning, and freight rates.

For liner operators, freight forwarders, beneficial cargo owners (BCOs), terminal operators, and supply chain technology providers, the real capability difference is not whether they acknowledge that congestion exists, but whether they can identify and quantify it in advance and adjust operations accordingly.

Key Developments: Identification, Quantification, and Causes

Identification: Anchorage Queues Are the First Signal

The number of vessels in anchorage being significantly higher than normal indicates that berth capacity is insufficient to absorb arriving volumes. Complementing this is berth waiting time: major hub ports average 6 to 12 hours during efficient operations, and once this extends to several days, it constitutes significant congestion. Container ships' port turnaround time is typically 24 to 36 hours; if it broadly rises to 48 to 72 hours or more, this reflects terminal capacity constraints rather than incidental factors.

The yard is the most easily overlooked link. Once utilization exceeds 75%–80%, the efficiency of locating containers declines, and additional container handling slows loading and unloading operations, creating a cycle of "congestion—high stacking density—more congestion." Declining carrier schedule reliability is often the other side of the same problem.

Quantification: A Set of Indicators Is Needed, Not a Single Number

The measurement framework listed in the guide includes: the absolute number of vessels in anchorage (compared with the historical average for the same terminal and same period), average berth waiting time, container dwell time (import containers typically 3–5 days at efficient ports, and 7–10 days or even longer at congested terminals), terminal productivity (25–35 moves per quay crane per hour is an efficient level), vessel exchange volume, gate turnaround time (reflecting landside efficiency), and call duration deviation—actual turnaround time exceeding normal levels by 30%–50% constitutes significant congestion. Terminal-level predictive congestion models can provide warnings more than 6 weeks in advance.

Causes: Supply and Demand, Labor, Equipment, and Landside

Surging demand is the most direct cause. Pre-holiday cargo rushes and tariff front-loading both create cargo volume peaks that exceed terminal design capacity; terminals designed for stable cargo volumes typically cannot absorb sudden 30%–40% increases. Ultra-large container ships further amplify fluctuations: ships of 18,000 TEU and above require loading and unloading 3,000–5,000 containers per call, occupy berths for long periods, and create concentrated pressure on yards.Labor shortages and labor disputes directly reduce terminal handling capacity; the congestion crises at U.S. West Coast ports in 2014–2015 and 2022 were both related to this. Insufficient quay cranes, chassis, and yard equipment also constitute bottlenecks. Landside infrastructure—rail connections, road corridors, and warehousing capacity—determines whether containers can leave the port quickly; sometimes the problem is not at the berth, but inland. Weather disruptions lead to port closures or reduced-speed operations. After the port reopens, backlogged ships queue, and congestion persists until handling capacity catches up with the queue.

Supply Chain Impact

The transmission path of congestion is relatively clear. The first is transit time: a single port can add delays of several days to several weeks. The second is cost: demurrage and detention charges rise. The third is production rhythm: uncertainty in arrivals forces factories to adjust production scheduling. The fourth is capacity deployment: carriers are forced to implement blank sailings or adjust port calls. The fifth is freight rates and congestion surcharges.

Particular attention should be paid to network cascading effects: a ship delayed by three days in Los Angeles will arrive three days late at every subsequent port in its rotation. Local congestion thus turns into schedule disruption across routes and regions, which in turn affects the pace of fulfillment of international trade contracts.

Port Impact Analysis

Differences at the terminal level determine the actual impact. Data from MarineTraffic shows that ports regarded as “congested” are often not calculated separately by individual terminal. This means whether congestion affects a given operator depends on whether the specific terminal its vessels call at is congested. For shipping lines, freight forwarders, and BCOs, identifying the terminals that are actually congested at present is more operationally valuable than debating global port congestion rankings.

Capacity conditions at major hub ports. Singapore is the world’s second-largest container port, with annual throughput exceeding 37 million TEU. Constrained by geographical space, peak-season berth waiting times can extend to several days. Shanghai and Ningbo Zhoushan are the world’s largest container ports by throughput, experiencing periodic congestion during peak seasons, pandemic lockdowns, and typhoon seasons; the two-month lockdown in Shanghai in 2022 caused ships to wait weeks for berths. The Los Angeles/Long Beach port complex experienced severe congestion in 2020–2022, with more than 100 ships at anchorage and peak berth waiting times exceeding 20 days; since then infrastructure investment has improved conditions, but it remains vulnerable when cargo volumes surge. In Europe, Antwerp and Rotterdam experience seasonal congestion during the Q3 and Q4 peak seasons and during labor actions.

Regarding the Red Sea, Suez, and Panama Canal. This reference material does not provide specific data or analysis on the above routes and waterways; its framework focuses on quantifiable indicators such as berth waiting, yard density, and call duration. Relevant diversion variables need to be assessed separately with dedicated data, and this article does not speculate.

Regional Impact

Asia-Pacific: Congestion in Shanghai, Ningbo Zhoushan, and Singapore has clear seasonal and event-driven characteristics, directly affecting schedule reliability on Asia–North America and Asia–Europe mainlines.Europe: Peak-season pressure and labor risks in Antwerp and Rotterdam affect the collection and distribution rhythm of Northern European gateways.

North America: The San Pedro Bay port complex still has a capacity ceiling under cargo volume spikes, and its landside rail and road connections are the key variable determining whether yards can be cleared in time.

Middle East, Latin America, and Africa: The reference materials do not provide congestion cases or quantitative data for the above regions, so this article does not make extended judgments. Relevant markets need to be assessed separately based on local port and shipping route data.

Industry Perspective

For liner companies, congestion means dual pressure on schedule reliability and blank sailing costs; for freight forwarders and BCOs, it manifests as higher freight rates, surcharges, and inventory carrying costs; for terminal operators, the core is matching yard density with equipment and labor allocation; for logistics technology providers, the opportunity lies in integrating AIS vessel positions, port call information, and operational indicators into continuously visible real-time monitoring and forecasting capabilities.

The common thread emphasized by the guide is: leading institutions turn congestion from "after-the-fact explanation" into "ex ante assumption," completing operational adjustments before congestion affects their own ships or cargo. For shippers, this shift is equivalent to turning logistics risk from passively borne into actively priced.

Future Outlook

Three directions are worth tracking. First, the accuracy and lead time of predictive modeling—terminal-level warnings of more than 6 weeks are becoming an actionable planning tool. Second, capacity investment at terminals and on the landside—improvements in Los Angeles/Long Beach show that investment is effective, but structural fragility will still emerge under demand spikes. Third, the unification of measurement scope—assessing congestion by terminal rather than by port will change liner companies' port call arrangements and shippers' procurement and inventory decisions.

Conclusion

The essence of port congestion is a mismatch between terminal handling capacity and arriving cargo volumes, and its impact spreads outward through four paths: schedules, yards, landside, and freight rates. The actionable approach is not to wait for congestion to ease, but to establish an indicator system centered on berth waiting time, yard utilization, and port call duration deviations, and embed it into schedule planning, capacity deployment, and inventory decisions. For global logistics and international trade, the level of congestion management is becoming a foundational capability for measuring supply chain resilience.