A single crane's capacity did not always set the practical maximum size of a movable caisson. Two cranes could share a tandem lift when one crane alone could not move the barrier. In the dockyard example recalled here, photographs and written discussions showed that this was the actual method used. Coordinating the cranes made the lift difficult and creates serious safety problems by modern standards. The example qualifies estimates of caisson size limits based only on the capacity of an individual crane.
Notable Point · 3:37:24-3:38:28
How tandem crane lifts extended caisson size
A caisson's apparent crane limit could be overcome by coordinating two cranes, although the lift became much harder to execute safely.