TT Talk - Container weighing – control and enforcement
- Date: 25/09/2013
- Source: TT Talk 179
One aspect of the container weighing debate has concerned the way in which the port and terminal industry will participate. IAPH supported the proposed amendment to SOLAS, while terminals have sometimes seemed less enthusiastic. As the law comes into focus, what are the possible impacts for container terminals?
The new SOLAS regulation continues to place responsibility for gross mass on shippers. The revised legislation prescribes two methods by which shippers may obtain the verified gross mass of a packed container:
"Weighing the packed container using calibrated and certified equipment; or
Weighing all packages and cargo items, including the mass of pallets, dunnage and other securing material to be packed in the container and adding the tare mass of the container to the sum of the single masses, using a certified method approved by the competent authority of the state in which packing was completed."
However the verified gross mass is obtained, it needs to be communicated to the line and terminal, through the shipping document, ‘sufficiently in advance to be used in the preparation of the ship’s stowage plan’. If the verified gross mass is not available it cannot be loaded onto the ship.
Of course, if a container is delivered to a port/terminal without the required information, the shipper or forwarder can ask the terminal to obtain the verified gross mass by weighing the container. The responsibility of container shippers and packers is nothing new, but the change will give terminals the opportunity to provide a weighing service where there is no verification available before the unit arrives at the port.
Ports and terminals have rightly been exercised as to how the new legislation will affect their logistics flows. The questions include how best to verify container weights, how to handle the commercial and administrative aspects, and what action to take if a container is found to be misdeclared or overweight. Since implementation of the new regulation is likely to be in July 2016 (in accordance with the provisions of SOLAS itself) there is time to prepare.
Meanwhile there are several alternatives available to weigh containers in terminals…
Weighbridges at or near the terminal entry gate
Weighbridges ascertain the total weight of the truck with the container when entering the terminal. The truck then has to pass the weighbridge again when exiting empty so that its tare weight can be deducted. This may be impractical where the truck carries two 20’ containers, since it would need to pass several times in order to determine the weight of each container. Similarly, the traditional weighbridge may be disruptive if the truck is picking up another container on the way out of the terminal.
Fixed weighbridges may not be logistically well placed for containers arriving by rail or inland waterway. They are, however, the most accurate means of weighing containers.
General weighing systems on handling equipment
Most cranes and container-handling equipment have weighing systems either for safety or stability purposes. These systems are mostly fitted to the rope anchors or into the shafts of the rope sheaves on the trolley. They are not very accurate and they have to take into account the changing rope weight depending on the lift height of the spreaders.
Where RTGs are equipped with anti-sway systems, then weighing from the trolley becomes even more difficult. The biggest problem with such systems is that they cannot weigh each container individually when twin-lift spreaders are used.
For the most part, these systems are orientated towards ‘safe working load’ issues. As a result, accuracy is a lesser priority and integration in the terminal operating system or ship planning software not generally considered at all.
Twistlock load sensing
During the progression of the debate about container weighing, two twistlock-based technologies have emerged on the market, the first using traditional load cells installed under the twistlock mounting and the second bonding a fibre-optic line into centre of the twistlock. Both have been implemented and integrated in operational settings.
While each operator would need to evaluate such technology, it seems that the fibre-optic option, developed by LASSTEC, is well-placed and major spreader makers, such as Bromma, RAM and STINIS, now will install this system during factory production. LASSTEC has this week been purchased by the Conductix-Wampfler Group, providing the industrial muscle to capitalise on the changing regulation. The fibre-optic sensor measures the elongation of the twistlock shaft, which then allows the load on the twistlock to be calculated to +/-200kg per container through the whole measuring range. This particular technology uses standard twistlocks, requiring no modifications to the spreaders and provides a measuring range far exceeding the twistlock rupture limits.
Enforcement – where, when and so what?
A port exists for the smooth flow through of freight. Therefore, for it to participate in the weighing solution, operations must not be overly disrupted. As such, a logical place to install a weighing system could well be the container yard. In order to comply with the IMO regulations this needs to provide accuracy and timeliness; there must remain some questions about the latter. However, practically every container will pass through the yard, whether it arrives by road, by rail or inland waterway – and can be weighed during the lifting process.
Since the ‘terminal representative’ is now to be written into the law, it seems inevitable that the port/terminal will become the ‘policemen’ to ensure that the ‘verified’ gross mass is both available and reasonably accurate prior to loading.
At this stage, twistlock load sensing seems the strongest enabler to the port process. Moreover, this technology has multiple safety benefits, including ‘snag load’ detection and identification of eccentric cargo packing. Additionally, experience suggests that the technology could deliver further benefits for terminals, such as equipment lifecycle monitoring and consequent safe prolonged component usage. Time will tell.
We hope that you will have found the above interesting. If you would like further information, or have any comments, please email us, or take this opportunity to forward to any colleagues who you may feel would be interested...
We look forward to hearing from you.
Risk Management Director, TT Club