Our client in Zeebrugge has a total of seven cranes in operation, of which five will be adapted. To raise the height, the cranes are temporarily moved to a 'construction site'. It is, of course, important that the normal terminal activities experience as little disruption as possible. Despite their similar age, the operating hours for each crane are considerably different. The cranes have been placed in order from one to seven, with three and four by far the most intensively used. This is the result of the lay-out of the quay. By scheduling the cranes in order of the number of operating hours, the arrangement of the cranes can be revised without delivering extra transport costs to the customer. The advice is, therefore, to place cranes three and four at the ends of the quay; where they will be used less. This will ensure that the fatigue of the cranes is spread effectively.