It’s a problem worldwide. Ships getting bashed by container cranes; straddle carriers nearly losing their cabs as they stray into the path of a crane spreader; not to mention the damage to containers as a misaligned spreader bounces off its side.
The hurly burly of life on the waterfront, as three or four elephantine straddles line up to service a couple of mammoth shipto- shore cranes, inevitably leads to a few scrapes. The container terminal at Lyttelton Port of Christchurch (LPC), handling 200,000 TEUs per annum, has incurred on average five crane to straddle accidents and two crane to ship collisions for each of the past three years. Fortunately, none have resulted in injury.
For bigger ports, the problem is much greater. Damage to critical infrastructure like radars has caused ships to be laid up in port awaiting new parts – a costly exercise for shipping lines and ports alike. Injury to personnel can lead to massive insurance liabilities, not to mention the consequences for the workers concerned.
An innovative solution
Rather than waiting for their luck to run out and human error leading to tragedy, LPC, its crane supplier Liebherr, and local company Computer Engineering Ltd have come up with an innovative solution involving crane mounted lasers, that automatically detects obstructions between the crane’s legs (in the case of the straddle carriers) or between the crane trolley, the end of the boom and the ship as it is loaded.
LPC specified the fitting of the Sick LMS laser unit for the installations. A laser sited between the crane’s legs looks for any object in the area which is taller than two containers (which can only be a straddle carrier, as no more than two containers can be stacked under the crane). The laser is sensitive enough to be able to identify the lane the straddle carrier is in and signal the crane control to prevent the crane trolley from getting closer than one full lane width from the obstruction.
Another Sick LMS laser unit is mounted on the boom tip which then scans landward and warns the driver of obstructions such as ships cranes, masts, radars or even the ship’s superstructure. The crane control prevents long travel on the crane if a collision is imminent.
The laser units have been fitted and tested on LPC’s newest shipto- shore crane, built by Liebherr at its Killarney, Ireland facility. The port’s two existing cranes, an older Liebherr and a Paceco, will also be fitted with the system as they are refurbished to match the new crane’s functionality. LPC’s Maintenance Manager, Mike McGlinchey, says the new technology has proven to be a flexible and cost effective solution.
The lasers have been operating for three months and to date there have been no incidents. On the expectation that the accident register continues to be clear, he expects the collision avoidance system to pay for itself, in terms of loss from damage and lost productivity, within a year.