Compare Port Congestion Using Matching Call Measures

Key takeaways

• Match the event being measured before comparing durations.
• Separate waiting, berth activity and complete-call measures.
• Review the composition and period of each sample.
• Translate a comparable historical result into a call-specific question, not an automatic routing decision.

This original framework contains no current congestion rankings or port forecasts. It explains how to assess the meaning of a comparison before applying it to a commercial programme.

Define the decision before choosing the metric

A desk comparing alternative receiving arrangements may care about the complete programme, including the relevant service and onward requirements. A performance review may instead examine a particular part of the port call. These questions need different boundaries.

State the start and end events for the chosen measure. Waiting before a service begins is not the same as the duration of the service itself. A complete-call measure may include both and other activities, depending on its definition.

Do not compare a waiting-only figure for one option with a broader port-stay figure for another and call the result a congestion ranking. The numbers can both be accurate while the comparison is invalid.

If the available evidence does not support a common boundary, explain the limitation. It may be possible to compare narrower components, or the desk may need additional information before drawing a conclusion.

Match the call population

The CPPI methodology groups container calls by ship size and call size for comparison. CPPI methodology note

For the desk's own analysis, identify the vessel and service characteristics that matter to its question. Do not assume that an aggregate covering different cargo services represents the nominated vessel's experience.

The amount and nature of work can also differ between calls. A longer observed stay may accompany a different service scope rather than establish a worse performance for comparable work. The report should identify that possibility instead of labelling every additional hour congestion.

Where the candidate arrangements involve different services, the comparison may need to assess the complete commercial outcome rather than force them into a single performance metric. A broader service can take longer while still meeting the programme more effectively under the actual circumstances.

Build a like-for-like comparison table

The following fields are an original analytical template. They help the reviewer decide whether the evidence supports a meaningful comparison.

Do not treat every mismatch as fatal. Some can be explained, adjusted with a defensible method or separated into distinct comparisons. The important point is to make the relationship visible rather than hide it behind a single ranking.

If an adjustment is used, retain the original observation and explain the transformation. The reader should know which result came from the source and which was constructed by the analyst.

Compare the distribution, not only a headline average

A single summary measure can conceal variation between calls. The mean and median describe different aspects of the observations, and neither alone provides a promise for the next vessel.

Use a summary appropriate to the decision and preserve the method. If the commercial concern is exposure to longer outcomes, a central measure alone may not answer it. Examine the relevant observed variation where adequate evidence exists, without inventing probabilities from a small or poorly matched sample.

The sample's composition matters too. A change in the mix of call types can change an aggregate measure even when comparable groups show a different pattern. Check the underlying groups before attributing the entire difference to port performance.

Keep sample limitations explicit. A precise average from limited observations should not be presented as a universal characteristic of the port or terminal.

Fictional case: the shorter number covers less activity

Imagine a fictional desk comparing two possible receiving arrangements. The first report gives a waiting-time estimate before service. The second gives a historical complete-call duration covering waiting and the service period. The desk initially prefers the first option because its number is smaller.

The review finds that the comparison has no common time boundary. It also finds that the historical calls do not fully match the proposed service. The numerical ranking therefore cannot support the original recommendation.

The team requests the relevant components for each option and prepares separate scenarios where current evidence remains uncertain. It compares the programme consequences using consistent assumptions, while preserving the historical observations as context.

The corrected analysis may still favour the first arrangement, but it will do so for reasons the evidence actually supports. It no longer treats a narrower measurement as proof of a faster complete programme.

Translate the time comparison into a commercial one

Even a valid time comparison does not settle the choice. The alternative may change freight, port services, inland movement, receiving arrangements or other relevant costs. Identify the actual incremental consequences rather than assuming that shorter time always means lower complete cost.

State whose decision is being assessed. A vessel owner's employment-time concern can differ from a cargo interest's delivery concern. A shared event does not necessarily create the same economic effect for each party.

Keep contractual recovery separate from observed performance. A duration difference does not itself establish entitlement to payment. Check the actual terms and obtain the relevant assessment before including a recovery assumption in the commercial model.

The comparison should lead to a specific decision boundary or evidence request, not a claim that one port is universally better.

Preserve current-call uncertainty

Historical performance and current call planning have different roles. A comparable historical dataset can help frame scenarios, but the nominated vessel's actual programme still requires relevant current information.

If the service location, cargo readiness or other material condition changes, reassess the comparison's relevance. Do not simply update the date on the same table and carry forward the earlier conclusion.

The desk may need to proceed with conditional alternatives while awaiting confirmation. Label the scenarios and identify which missing input could reverse the preference. A transparent conditional comparison is more useful than an unsupported precise forecast.

Use the result proportionately

The final recommendation should state what was compared, the evidence limitations and the practical consequence. It may support further enquiry, a revised planning assumption or a more detailed evaluation of an alternative arrangement.

Avoid generalising beyond the population and period reviewed. A result for a defined call group should not become a blanket judgement about every cargo service at the location.

Retain the comparison basis with the conclusion so another desk can reassess it when the programme changes. The value lies in a defensible link between evidence and action, not merely in producing a ranking.

Common mistakes

Comparing waiting time with complete-call time. Match endpoints before interpreting the duration difference.

Ignoring different workloads. Check whether the calls represent comparable services.

Mixing summary statistics. Preserve whether each figure is a mean, median or another measure.

Turning a historical comparison into a berth promise. Obtain current evidence for the actual nominated call.

Where Zeaclub fits

Zeaclub provides a multi-party shared workspace for owners, charterers, brokers and port agents.

Zeaclub offers digitalised procedures across the voyage workflow.

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