Automation does not negate the need for adequate RTG collision prevention finds John Bensalhia
The rubber-tyred gantry crane is an undeniable cornerstone for efficient port operation. As such, this workhorse has been a prime candidate for enhancement, first through electrification and more recently with automation. But no matter how many improvements are made, safety still needs to be the number one priority.
For Liebherr’s Trevor O'Donoghue, the primary concern is to provide a safe working environment for crane operators, auxiliary personnel and truck/trailer drivers. A chief issue is that of potential collisions.
In a recent report conducted by the TT Club, a principal concern was that of stack collisions. Statistics revealed that 19% and 82% of claims were attributed to quay cranes and yard cranes respectively. Operation of rubber-tyred gantry cranes was identified as a potential risk element, specifically through collisions.
To this end, a number of solutions have been introduced to combat this problem. APM Terminals, Bahrain has introduced a global test site for a new RTG collision prevention system. The aim of this initiative (developed between APMT and Siemens) is to prevent collision accidents between RTGs and containers: the data gleaned from the tests will drive safety improvements.
“Nowadays there are plenty of different types of anti-collision sensors available, including for example ultrasonic, laser and radar technologies,” says Mika Virtanen, vice president of Kalmar's RTG and STS Cranes. “In the past, the main issue was usually to prevent collisions between two cranes, but today’s modern sensors can also be used to detect if a person goes to a wrong place during operation.”
Konecranes’ Thomas Gylling agrees that container stack collision prevention is today a key feature of RTGs: “We are delivering increasingly more RTGs with this feature integrated. Crane-to-crane collision prevention as well is becoming a standard feature. In unmanned and autonomous ARTG operation these both are of great importance.”
Mr O'Donoghue outlines the many anti-collision systems in operation on a Liebherr RTG. Stack profiling, for example, allows the machine to calculate a safe path for the spreader and attached box and will prevent collision with the containers in the stacks.
“Integrated within the RTG are also proximity sensors that prevent the machines colliding with each other as they operate on a stack. These systems may require driver intervention in responding to an alert or be autonomous in that there are built in limits that prevent two machines having a close approach to each other. Ground level sensors allow for collision avoidance with obstructions on the path of travel.”
Other anti-collision aspects include whisker anti-collision and auto steering. These prevent the structure of the RTG from colliding with the stacks. In addition, a number of cameras can be strategically installed, which provide the driver with extensive visibility. The camera views allow the driver good vision of the area that cannot normally be seen comfortably.
Increased automation will further aid RTG safety and is an area that manufacturers are focussed on.
Automation is a hot topic at Konecranes Port Cranes, confirms Mr Gylling: “Konecranes released the Automated RTG system to the market a few years back, offering all the benefits of automation to RTG terminals. Since then, we have seen a strong interest increase of RTG automation among the terminals, since the potential for this is huge. The ARTG system utilises a next generation automation platform, including fully automated stacking, Remote Operating Stations (ROSs) for truck handling and the related container yard infrastructure.”
When it comes to buying an automated rubber-tyred gantry crane, every port is different in its needs and demands. “The RTG operation may be integrated with the TOS and different levels of automation may exist within the port,” says Mr O'Donoghue. “Factors such as productivity, reliability, availability, cost per box moved, cost of spares and maintenance, integration with the TOS, environmental issues and lifetime costs will also be considered and the relevance or importance of each of these issues will change from port to port.”
Mr Virtanen adds that automation and remote control allow the operator safe and efficient movement. “Automating certain moves of the crane means that the crane is driving automatically. The operator’s task is to monitor that the operation goes safely and smoothly. In addition, the introduction of remote control on the crane means that the driver is no longer on board the crane, but in the office working via remote control desk.”
To ensure thorough knowledge of RTG operation, training is essential. Mr Virtanen says that training should come from two sources: the manufacturer – “to learn the features and characteristics of this specific crane model, its safety features, to mention a few” - and the terminal staff – “to learn the local operation practices of the terminal, local safety rules, and other local safety procedures”.
Mr O'Donoghue says that training is an issue that will be determined by the port and the skill of the operator. “Training can take place on the machine in a live port environment or the operator could take advantage of an RTG simulator such as the Liebherr LiSIM, which has been designed using Liebherr components and systems to provide a true to life simulation of Liebherr RTGs.”
Looking ahead, Kalmar believes that there are still significant gains to be made from further RTG development. “There is a lot of potential in the field of developing the operational efficiency of the crane,” says Mr Virtanen, who adds that the introduction of a higher degree of automation and remote control is key to future development in the sector.
Trevor O'Donoghue questions the level of human involvement in the future: “As technology, remote control and automation develop, we will reach a point where the reliance on the human will decrease, and perhaps, cease altogether.”
Perhaps the stuff of sci-fi films and TV programmes may not be as remote as we once thought.
Sensors work overtime to improve safety
The latest inroads into sensor and laser technology have paid dividends when it comes to collision prevention for rubber-tyred gantry cranes. Sensitive, precise, reliable: these new systems are highly effective.
Take Banner's R-Gage Q120RA-AF2 sensor. It can detect the presence of any obstacles and prevent resulting collisions. The advanced technology features a narrow beam pattern, high sensitivity and long range which come together to alert the operator of anything in the way. The sensor gives off a beam of high frequency radio waves from an internal antenna, with some of that energy reflected back to the receiving antenna. Based on that signal, it's possible to judge the distance between the sensor and the object, thus alerting the operator of any obstacles.
SICK, meanwhile, have introduced laser measurement systems (LMS III) to alert operators of any obstacles and prevent collisions. This technology is in use at the MSC Terminal in the Port of Valencia.
The system is placed on the lower side of each crane leg. The scanning fields are adjusted to the speed of the crane, which means that the scan field is small at low speed, and grows as the vehicle's speed increases.
If an obstacle is present, the operator receives a message. The operator or system can then either slow down or stop the gantry before the collision occurs.
These devices not only mean fewer collisions and safe operation, but also lower repair costs, increased systems availability and greater efficiency.
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