“This type of incident can result in serious injuries to workers and be very costly in repairs and operational downtime,” noted Laurence Jones, TT Club’s director global risk assessment. However, such incidents can be prevented, or at least the collateral damage caused can be restricted by having appropriate procedures in place and ensuring that they are followed.
Essential elements include having effective national and local weather forecasting systems and ensuring that operational procedures respond appropriately when sufficient warning is forthcoming. In addition, good practice dictates that storm pin or tie-down facilities and procedures are invoked.
Furthermore, appropriately designed braking systems, which are properly maintained, can significantly help in conditions of sudden wind bursts. There are two major windstorm issues to be considered: protection against forecast strong winds, and protection against sudden local winds, or micro-bursts. â€¨â€¨
In the case of forecast strong winds, storm pins and tie-downs of sufficient number and size to hold a crane structure stationary are required to protect quayside cranes. Storm pins are vertical sliding pins mounted at suitable positions under each leg of the crane, and dropped into sockets set into the surface of the berth. The pins must be interlocked with the travel motion so that the crane can only be moved when the pins are disengaged.
Storm tie-downs are connections on the crane, normally at the four corners, where suitable slings, chains or bars of appropriate size and number are fitted to connect to anchor points in the terminal pavement. These anchors must be able to hold the loadings of the crane under potential wind conditions. â€¨â€¨
The other situation of primary danger is the occurrence of micro-bursts. In the worst circumstances, a strong wind blowing in the same direction in which the crane is travelling mean that the unwitting driver is unable to stop the motion of the crane. To deal with these situations, suitable storm and service brakes should be fitted to the crane. These are not however, an acceptable alternative to pins or tie-downs for forecast weather conditions. â€¨â€¨
There are a number of different systems used for storm brakes or, as they are sometimes called, parking brakes. These include rail clamps and railhead brakes. These are static brakes, i.e. they are only applied when the crane has stopped moving.
They normally operate if the emergency stop is activated and, unless severely damaged, will help prevent a stationary crane from being pushed along by the wind. Their main purpose and benefit is to park and anchor the crane between normal operations, without the need to apply the storm pins or tie-downs. â€¨â€¨
If rail clamp and railhead brakes are applied when the crane is moving, both the brakes themselves and the crane rail can be damaged. For this reason, wheel brakes should also be installed; these are normally disc brakes mounted on the crane wheels. Finally, the service braking system forms the normal operating brake. This is part of the motor and gearbox of the crane, which slows and ultimately stops the crane during daily working. â€¨â€¨
Apart from accurate weather forecasting and adequate technical measures, Jones emphasises that both maintenance and training are crucial to safer procedures. “Investigations of these incidents have shown that most were due to, or made worse by, many of the service brakes and park brakes being inoperative due to poor maintenance,” he observed. â€¨â€¨
“When a driver is faced with a crane being blown along the quay, the natural tendency in many cases is for him to try to move the crane back into the wind. However, by doing this, the crane service brakes are lifted and become ineffective. The driver must immediately hit the emergency stop, applying the service brakes as well as the storm or parking brakes,” explained Jones.