Quay Simulation - Determine Optimal Quay Capacitiy, Service Level and Quay Crane Requirements in Times of Volatile Transport Volumes

Varying cargo trade volumes, forcing shipping companies to adapt their vessel services constantly. As a result, vessel shipping routes, vessel sizes and number of vessels on route are being frequently changed. Cargo volumes have aggregated, and container vessels are being taken out of operation. How can the cargo terminal operators react to the temporary reduction in cargo terminal throughput volumes and reduced number of vessel calls? How do they reduce operating cost while retaining required flexibility to quickly adapt to new situations?

During discussions with our customers and partners, one measure came up repeatedly - temporarily taking quay cranes out of operation. This measure, firstly, reduces running cost of the quay cranes directly. Secondly, it enables the terminal operator to ascertain other follow-up measures, such as taking other equipment out of operation (RTG, AGV; trucks), reassigning work force or closing whole berths. 

Such measures offer huge cost savings potential. Depending on the cost levels of labour, energy, and maintenance, operating just one quay crane costs about USD 250 – 350 per hour. Taking a single quay crane out of operation for one month can thus save up to USD 150,000. 

Despite the obvious saving potential, it is not a simple decision to take for terminal operators. Whilst deciding the number of required cranes and berths is a common business on a daily and weekly basis, assessing the requirements on a longer period is a complex task, which relies on numerous assumptions. The quest at hand for the terminal operator is: How to ensure that the agreed service quality covering the resulting vessel waiting time, port stay time, quay crane productivity, vessel productivity or quay crane intensity are met with reduced equipment capacity for a longer period? 

One of the best tools to provide reliable information on the quay performance is a dynamic quay simulation. It is a powerful instrument to analyse the unique quay crane and quay crane allocation behaviour for many different container volumes and vessel berth schedule situations, whilst considering all relevant influencing and terminal-specific factors. Quay simulation is not a crystal ball, but its results come with an average accuracy of about 98% percent, a figure close to reality. That is why quay simulation is so attractive to the decision-makers. 

In my work so far as a container terminal simulation specialist, I have been requested to investigate the quay performance for ever growing container volumes forecasts. Now the situation has changed, and the question has diverted more in the direction of what happens if vessels are not calling the port anymore. And luckily, the quay simulation is still applicable to this new situation in the same way as before. Only the waterside influencing factors and investigated scenarios need to be changed. 

In my opinion, this is exactly where a detailed modelling and thoughtful selection of investigation scenarios will provide a sound basis for analysis and ultimately enable fully informed decision making. Besides answering the question of interest, going through the process of a simulation study provides a deeper understanding of interrelations between vessel calls and quay operations or the quay operations itself for situations and times that are yet unchartered land to many operators. 

Let us have a closer look on some used cases for quay simulation. 

Use Case 1: Determining the requirements of quay cranes and berths for different vessel traffic scenarios

Different vessel traffic scenarios consist of different container volumes, different vessel call patterns at the quay or a combination or both. In Use Case 1, these vessel traffic scenarios are defined as input for the simulation and tested in response to the number available quay cranes and berths. By comparing the resulting KPIs of the simulation runs for each scenario, the required number of quay cranes can be determined.

Use Case 2: Determining the maximum quay handling capacities

The maximum quay handling capacity is the overall volume of container which can be loaded and discharged within a defined time period. In Use Case 2, specific sets of available quay cranes, berths and vessel call patterns are defined and tested in response to a stepwise increase of cargo throughput volumes. Once the resulting simulation KPIs (Berth Occupancy Rates, Vessel Waiting Times, or Vessel-In-Port Times) exceed predefined limits, the maximum quay handling capacity per set can be identified. Furthermore, this use case informs about the volume related flexibility of the quay.

Use Case 3: Quantifying the achievable service levels for different traffic scenarios

Getting a picture of resulting customer service levels for different traffic scenarios is mandatory to ensure high service quality in times to come. Consequently, Use Case 3 provides an overview of inter alia resulting vessel waiting times, vessel port times, vessel handling times, and vessel productivities in response to quay crane and berth quantities for each traffic scenario.

Use Case 4: Quantification of the savings potential imposed by temporary shutdowns of quay crane

This Use Case is a combination of the quay simulation and a subsequent cost calculation assessing the savings potential. At first, the number of required quay cranes is determined by testing defined vessel traffic scenarios in response to reduced quay crane quantities. The minimum number of required quay cranes upholding the service levels will be considered as lower boundary. In the next step, the related costs are calculated for all tested quay crane quantities, thus estimating the potential savings for reduced number of quay cranes. Besides the number of quay cranes, the cost calculation is enriched by insightful simulation results such as vessel operating times, quay crane operating times, vessel waiting times and other utilization rates, drawing a complete picture of operations.

Long story short, quay simulation provides you the first and foremost answers on how your quay operations and set up must look like in different scenarios to come, with a proven level of accuracy. With this knowledge at hand you can prepare an action plan for different materializing situations, that is in line with fulfilling your quay side obligations, ultimately increasing your resilience significantly.

I would like to encourage you to be brave, and not to avoid this complexity. And see it more as a battle for erasing the fog of uncertainty around future quay handling requirements, using quay simulation as the brightest spotlight of all.

This article was written by Maxim Neiser, HPC.