Analysis of TT Club’s claims experience continues to highlight the vulnerability of quay cranes, other handling equipment and containers to major weather related incidents at marine terminals. Despite the large mass, it is not uncommon for these cranes to be blown along the crane rails, potentially into other equipment or toppling over, giving rise to extensive damage.
Equipment and property damage incidents in container terminals continue to feature in the industry trade press all too frequently. While a number of these involve third party impacts, and some relate to lack of maintenance or improper procedures, a prevalent factor is the exposure to windstorms. The ship-to-shore or quay crane is one of the most valuable assets of a marine terminal in terms of cost and operational dependence.
“quay cranes are particularly susceptible to wind”
Due to their size, profile and location on the quayside, quay cranes are particularly susceptible to wind, and care must be taken in the design and operating procedures to protect the asset. The associated risks are not confined to cranes; there have been multiple examples of localised windstorms affecting other terminal handling equipment or causing empty containers to fall from stacks.
These types of incident can result in serious injuries to workers and, particularly when quay cranes are involved, can be very costly in repairs and operational downtime. The impact of windstorms can be mitigated by having appropriate procedures in place and ensuring that they are followed. Essential elements include having effective national and local weather reporting systems and ensuring that operational procedures respond effectively when sufficient warning is forthcoming.
Additionally, the stack profile of empty containers should be considered in locations susceptible to windstorms; high, narrow stacks are particularly vulnerable. In certain locations there may be capacity challenges, but due consideration should be given to the planned profile of stacks, specifically the height and depth. Stacks should be aligned so that the units’ longitudinal axes are in line with the predominant wind direction. In advance of forecast storm conditions, particularly where stack heights cannot be reduced, additional measures could include interlinking with locking cones, straps or webbing to create a heavier and more stable mass. Where stacks are more than four high, consider a ‘pyramid’ formation.
For quay cranes, good practice would dictate that storm pin and tie-down facilities and procedures are invoked. Well designed and maintained braking systems, can significantly help in conditions of sudden wind microbursts. There are two primary windstorm issues to be considered: protection against forecast strong winds and protection against sudden local winds called microbursts.
Frequently the design of equipment and the procedures underpinning safety are based on the maximum wind speed recorded at the location in question. The industry is witnessing windstorms occurring more frequently and in historically unusual locations to devastating effect due to climate change. It is imperative that operators recognise these changes and where appropriate re-assess the risks accordingly.
Procurement of quay cranes should involve consideration to features such as storm pins and storm tie-downs, of sufficient number and size to hold the crane structure stationary. Thereafter, procedures should be developed to ensure that these safety devices are positioned, prior to the windstorm, to protect the asset. Unfortunately, while many terminals have storm-pins, storm tie-downs are less frequently specified.
It might be prudent to consider retrofitting storm pins and tie-downs for existing cranes. Are the average and peak wind speeds now higher than the wind speeds used for the maximum uplift calculations during initial design? Particular care should be taken where quay cranes have had their legs raised and/or booms extended; wind and uplift calculations should have been performed at the time of modification to ensure existing storm tie-downs and civil works were structurally adequate. Review may be necessary to consider whether further changes are appropriate.
“It might be prudent to consider retrofitting storm pins and tie-downs for existing cranes”
While forecast storms clearly present risks, the occurrence of microbursts, during which even the maximum forecast wind speed may be exceeded, create an additional and ongoing challenge. In the worst circumstances, unknown to the driver, a strong wind might arise, blowing in the same direction that the crane is travelling and the driver is unable to keep control. To deal with such situations, suitable storm brakes and service brakes are necessary. These are not, however, an acceptable alternative to pins or tie-downs for forecast windstorms.
Maintenance & training
Aside from accurate weather forecasting and adequate technical measures, both maintenance and training are crucial for safe operations. Investigations of microburst related incidents have shown that most were due to, or made worse by, service brakes and park brakes being inoperative as a result of poor maintenance. Simulation of such conditions is difficult; procedural training is critical in addressing this area of risk and ensuring that the crane driver is able to take the correct evasive action.
In summary, all physical supply chain operations will be exposed during severe windstorms. TT Club urges container terminal managers to review earlier climate modelling, their equipment, emergency plans and procedures in respect of windstorm risks. Doing so will ensure that all possible measures are taken to ensure property and equipment are adequately protected – and personnel kept safe.
We hope that you 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.
Source: TT Club