The number of tower cranes used on a structure is the total number of fixed cranes, or large tower-like cranes on fixed tracks, which were assembled or installed for use in building that structure during its construction phase. This includes cranes with horizontal or diagonal booms. It does not include mobile cranes, and it does not include tower cranes installed for renovation or demolition.

Each tower crane counts as 1 in this quantity, unless it is shared with another project through any one structure's entire construction phase. Thus, if a structure has 1 crane of its own and shares 1 crane with another structure being built nearby, then it counts 1.5 cranes (if it does not have exclusive rights to the shared crane during any phase) or 2 cranes (if both cranes belong to that structure during any part of the phase).

The count covers qualifying tower cranes across the construction phase, not merely a simultaneous peak. Continuous sharing can give a fractional contribution, while a crane used exclusively by the structure during any part of the phase contributes one under the stated rule.