Container cranes lag behind container ships by a generation

Shoreside infrastructure continues to suffer diseconomies of scale as container ships grow, adding a column per generation.

Shmuel Yahalom, Ph.D., Distinguished Service Professor of Economics and Transportation at SUNY Maritime College, said at CMA Shipping 2023 last week that each new generation of container ships will have a beam of 2.5 m, the width of a container, as a container has added lines looking for scale effects on the water.

“But what happens at the port? In port you deal with economies of scale because ships are bigger and it takes more time to unload and load a bay – not the whole ship, you can put many cranes on the ship. But the bay itself is bigger, no matter what you do, you have more time to unload, and that part was neglected in the analysis,” Yahalom said.

The effects of increased dwell time are compounded by the footprint of the cranes themselves, which, due to the footprint of the crane, often block a number of berths on either side of the one they are working on.

Yahalom measured bay time for ships — the time it takes to fully unload and load a single bay — and at a rate of 35 lifts per hour, found that the average estimated bay time for a ship increased by 4.5 hours each time , when a new ship class was introduced.

By comparing the required lifts per hour and minimum bay times across ship sizes, with cargoes from only 40ft containers and mixed bays of 20ft and 40ft containers, scale disadvantages in the port become more apparent with increasing ship size.

Yahalom found that crane productivity had increased by over 90% over the past 20 years, but ship bay size had increased by 202% over the same period.

“This shows that the port is catching up with the size of the ship, a ship generation behind. In the beginning they are always a generation behind, then two generations behind. So, under these circumstances, there will be no convergence.”

Duplicate container movements — removing and loading a container in the same elevator — offer only a 10% increase in efficiency, Yahalom said, as containers on deck must be cleared to access below decks.

Other methods of moving up to six containers at a time have been studied, but only work with such a high number of empty containers and only when unloading, as splitters are not designed to line up containers to lower them together, only to lift aligned containers.

Yahalom’s suggestion to solve the problem in the ports was better technology to improve movements per stroke.

Source: News Network.