first tower crane assembled

The assembly of the first tower crane used in a structure's construction occurs as soon as at least one crane becomes operational. This does not mean that the crane has reached maximum height, because it often enters service long before then, and is jacked up as the structure rises.

This event only applies to fixed cranes or cranes built on tracks; it does not apply to vehicle-type mobile cranes.

At least one qualifying crane must be operational. Delivery of crane sections or the start of assembly is earlier than this event; assembly of additional tower cranes later does not change the first crane milestone.