!["Operators may baulk at the cost but although this is not cheap, the current injuries and damages caused by stack collisions make [stack profiling] an economically viable investment," Laurence jones, TT Club](https://www.portstrategy.com/greenport-congress/wp-content/uploads/sites/5/2013/11/00_98060_Laurence-Jones.webp)
Collisions with stacks are still a relatively common occurrence at container terminals, but that needn’t be the case with today’s prevention technologies.
In fact, manual container handling facilities can take a leaf out of the book of automated terminals by installing stack profiling technology on yard equipment to reduce the chance of collisions, and in doing so reduce the possibility of costly downtime and in some cases fatalities.
TT Club statistics reveal that 82% of yard crane claim costs are caused by stack collisions with the spreader or a box under the spreader hitting the stack, often knocking boxes on to crane legs or a truck. Further, 19% of the cost of claims caused by quay cranes is stack collisions where the spreader or a box under the spreader hits the stack on the ship. This, TT Club believes, is totally preventable with the use of stack profiling.
Stack profiling employs a measurement or sensor system to identify the stacking pattern underneath an automated stacking crane, a rail mounted gantry crane or a rubber-tyred gantry crane.
Laser tag
The primary technology used is lasers for distance measurement. The lasers are mounted on the RTG and are constantly measuring distance from the machine to the container stack. An accompanying on board computer processes the reported measurements, processes telemetry from the crane PLC, and monitors the movement of the spreader. When a potential danger is recognised, the system works to prevent an accident.
Kalmar has used these measurement systems for some time in automated terminals on automated straddle carriers to help with inventory operations.
John Rosen, director product management at Kalmar, explains: “Currently, we are creating a new solution for manned RTGs that will use the same base technologies but will, instead, be providing a safety benefit.
“The purpose of the RTG solution will be to prevent containers being knocked over by the RTG spreader (or spreader with a container) as it moves over the stacks. These types of accidents are extremely serious, with serious consequences for equipment and people.”
For precise stack profiling the laser must be accurate within a range of several millimetres.
“It is critical that the right laser be used, and we are working with our partner vendor in hardware selection and solution design and conducting extensive testing to ensure that the system will work under all circumstances,” says Mr Rosen. “Additionally, the controlling software which will process the data will use algorithms to deal with other system errors which may come into play, such as RTG telematics or hardware failure damage.”
Manual need
Laurence Jones, risk assessment director, TT Club, believes the technology is a essential investment in non-automated terminals. “I would like to encourage manual terminals to do stack profiling in the same way as we use in automated terminals.
“Accidents are nearly non-existent in terminals with automated yard cranes,” says Mr Jones. “Some of these automated yard terminals that the TT Club insures have had no claims at all in the yard. With automated yard cranes stack collisions cannot happen due to having sensors and software to profile the position of all the containers in the stack and thus restricting the crane movement to prevent stack collisions.”
Stack profiling systems deployed on automated cranes can be installed on manually operated cranes at a cost of about $50,000 for a new crane and around $75,000 for a retrofit, according to TT Club estimates. “Operators may baulk at the cost but although this is not cheap, the current injuries and damages caused by stack collisions make it an economically viable investment.”
TT Club has had 339 claims in the last seven years from spreaders or boxes under spreaders knocking other boxes from stack. This can damage cargo, equipment and cause personal injuries, including fatalities and is entirely preventable with the installation of stack profiling.
Currently, the feature is available as an option on Kalmar RTGs. “The industry, though, is shifting its focus more and more to safety, and we expect that these types of important safety features will one day be standard on all equipment,” says Mr Rosen.
