It is generally advantageous to introduce an explicit hierarchy of work activities for the purpose of simplifying the presentation and development of a schedule. For example, the initial plan might define a single activity associated with "site clearance." Later, this single activity might be sub-divided into "re-locating utilities," "removing vegetation," "grading", etc. However, these activities could continue to be identified as sub-activities under the general activity of "site clearance." This hierarchical structure also facilitates the preparation of summary charts and reports in which detailed operations are combined into aggregate or "super"-activities.
Tightening of the prestressing cables of 30-cm mass concrete slabs, bridging an 11-m enlargement. Valencian Institute of Modern Art (IVAM), Valencia.
SOURCE:  A waffle slab with 40-cm-high system formwork, edge of (40+ 5) cm or (40 +10) cm, and prestressed ribs with two non-adhering stranded wires of or inches, could allow spans of 15 to 20 m, while simultaneously minimising the problem of deformations. It suffices for the deviation forces to oppose each other and cancel out the loads of the own weight to assure a horizontal mass concrete slab with zero deflection.
In addition, compressive prestressing reduces and cancels out rheological cracking in the slab (map cracking, shrinkages, etc.), which is so difficult to avoid in traditional reinforced concrete slabs.
After this brief introduction to waffle slabs through their main parameters, the following examines slab deformations, owing to their direct relation to the installation of direct adhered modular rigid flooring.
In the case of waffle slabs, the quantitative evaluation of deflections from formulas or mathematical models is even more complex, perhaps even unencompassable, because of the problems stemming from torsional mechanisms, the difficulty of quantifying these in waffle slabs, and the high degree of cracking that usually occurs in the compression layer.
The model of finite elements [PhD thesis of Luis García Dutari] and the model of virtual gantries, based on the concept of Effective Inertia [by . Branson] and adopted in Instruction EHE , as well as theoretical calculation models such as the CYPECAD software  , provide a qualitative approximation for foreseeing deformations.
Just as in beam and pot floors, this involves an approximation to waffle slab deformation, taking into account the following: